Betta with ballooned side

Orion, my Betta, has recently developed a really weird condition.

Backstory first.
I have two 2.5 gallon tanks, the National Geographic half moon. One housed Orion, the other housed Bellatrix. They're side by side, but didn't share any water or decorations. Each contains a (if I remember correctly) Anubias plant, large enough for the bettas to lay on. I've recently taken out the other decorations, so I can keep a better eye on them.

Orion and Bella loved each other, and he often made her nests. A month ago, though, she swelled up quite a bit. My grandfather, who I usually go to for advice, said that she was probably filled with eggs, and would pass them naturally. Her scales looked normal to me, so I just let it go. During that time, they had no contact.

About a week and a half ago, though, Bella passed away. I'm starting to suspect she had Dropsy and I didn't realize it. Orion seemed fairly normal, if confused about where she went.

Three days after, we noticed a small swell on his side. I immediately started researching, afraid he'd follow Bella's path. Unfortunately, I haven't found anything else like it. The lump rapidly ballooned up to an alarming size over the next few days. I'm afraid I didn't think to take pictures of it. The lump was probably as wide as he is, and about half his length.

I took him into Petsmart to see if they had a solution, and the young lady said she'd never seen anything like it, and suspected it was a tumor. She suggested I try the pea thing, just in case. When I got home, I put him in a smaller tank without any gravel, so I could monitor just how much he ate and pooed. I then cleaned his entire tank and changed his water completely, in case it was something in that. He did eat his pea, and seemed to be passing normally.

Two days ago, I returned him to his tank. He was given another half pea last night, but it looked like he'd lost some scales and his skin was starting to shred, we didn't have high hopes. This morning, I decided to just try and make his last days as comfortable as I could. I fed him two freeze dried bloodworms (His favorite treat) When he swam up from his usual spot to eat them, I noticed his lump had gotten bigger. The skin was stretched so thin I could kinda see into him. He tends to stalk his food from below, and he turned his lump side away from me. Moments later he turned it back towards me, and it was completely gone.

The only way I can describe it is that it popped while he was swimming.

I noticed no discoloration of the water, nor anything leaking out of his side. He has a small white mark on his side now, but it's not bigger than maybe three scales. It does look like it might be an open wound, though. He's not bleeding, and seems to be in no pain.

Throughout the course of this whole thing, he has been eating normally and acting as if the lump was never there. He's been a tiny bit more lethargic, but otherwise fine. This morning, before it popped, I even noticed he'd built me a bubble nest.

I went back to petsmart this afternoon, and they suggested I try treating him with aquarium salt. I've added the appropriate amount for my tank, and he seems to be doing well.

My current plan is to reduce his food for the next few days and try to monitor as much as I can.

I'm afraid I don't know what my water make up is. I use distilled water every time, and other than this month, my fish have always seemed healthy. Orion is my third fish (Flame, a male, was my first. He lived two years before dying of what seemed to be age, Bella was my second) I do think I have a bit of a habit of overfeeding them, but not that much.

I'll try to get s of his spot as soon as I can, but while not camera shy, he seems to think his other side is his better side.

 

Dropsy. Later stage. Most time it's terminal

 

I read that the tell for Dropsy was scales looking like a pine cone, and his do not. The lady at petsmart also said that it was not. if it is, though, what's the best way to prevent it?

Unfortunately, I'm currently traveling and unable relying on my mother for assistance in this. I think I have a photo of him now, and I'll try to post it tonight

 

So, update. Orion is just starting to show signs of pineconing. Developed last night, at least that I noticed. He looks like he might have a small swell near his mid region as well.

The wound from his side exploding is a healthy, healing pink color, and seems to be shrinking. However, on the other side of his body, it looks like he lost a single scale.

He hasn't eaten in days, and spends most if his time laying on the bottom of his tank. I tried adding aquarium salt to his tank three days ago, when I noticed the change.

I went out today searching for medicine, but neither petco not petsmart had any of the names I've seen floating around this forum. I ended up getting one that says it treats dropsy and that the guy at petco said was very good. It's labeled
"microre-lift
herbal actives
artemiss".

I moved him to a half gallon "hospital" this morning with some aquarium salt, then added his first dose of medicine at two today. By three, he seemed much more active and was swimming around his tank. By four he was back to laying around.

He interacts with me, and seems to respond to music, which I'm taking as a good sign. I've tried offering pellets, a pea, and blood worms, but no interest. I also noticed around six that he had a long white string hanging from between his lower fins. There's a chance there's a small one between his gills, but I was having trouble telling. He also seems to lean to one side when resting, but but when swimming.

My current plan is to do daily water changes, adding his medicine and Epson salts for the ten days the bottle recommends.

I also got some test strips and checked the water in his usual tank, but not the hospital. Readings are as follows.

No3 between 0 and 20 leaning closer to 0
No2 0
ph 7
Kh between 0 and 40, closer to 40
Gh between 0 and 30

What else can I do to help him? Is there anything I should watch for? What are his chances? He's a fighter, I know he wants to live, but I'm still really new to this fish caring thing, how can I best help him?

I finally downloaded the app, so I'll add a few photos.



His wound, two days ago.





HI'm tonight

 

Aquarium salts are not good to keep them in for a long time - epsom salts baths are used to help fish pass food (it is laxative) or to help get rid of excess water, like in the case of dropsy. Is his hospital tank heated? Is his normal tank heated?

The last picture is not that good of an indication for him, I'm sorry. HI'm not eating is not a good sign either, keep trying but make sure to watch him to see if he eats. If he has dropsy, make him as comfortable as possible before euthanizing him as in most causes it is impossible to cure (very few cases/stories otherwise), I myself have lost two betta to dropsy which was really saddening because I had had them to longest out of all the others.

Keep up the water changes, make sure the water temps are close, that is the best way to go about it. I don't use test strips so I don't know what to make of those readings...

 

Oh, poor thing.... I'm sorry I can't help I'm horrid with diseases and cures, but its probably most likely dropsy

 

You can still try Epsom salts to get fluids out (for dropsy), but you should get us the temperature of the water, too.

With a wound like that, chances are he's been infected by bacteria- maybe one that makes his scales fall off, another that causes dropsy, etc. If he doesn't get better after salt, try some medication as a last resort.

I pray he'll be okay.