Very Ill Betta- Euthanize or Continue Treating?

I’ve been wrestling with the decision of whether I ought to continue treating my betta or begin the process of euthanizing him with clove oil. I am deeply saddened by my betta's suffering, and I worry that his pain was precipitated by something that I have done or failed to do. However, I am mindful that my guilt and rue cannot distract me from acting in the best interest of my betta, even if this entails euthanasia.

That said, I have observed some improvements in my betta’s condition over the past few days. He is swimming more, though he still is still spending the bulk of his time resting on the floor of his breeding net box. He also appears more alert, particularly when I’m feeding and interacting with him. I’d like to continue trying to treat him while he’s eating and improving.

My betta’s symptoms have evolved in a manner that is suggestive of columnaris and fin rot. He recently started developing a white or blanched patch in the middle of the black patch that formed on his body at the beginning of his illness. His fins have shown further signs of fin rot, with some black discoloration along the tips. He also seems to be itchy - he periodically scratches his body along the netting of his breeding box.

Yesterday, I started medicating my 10 gallon tank with a tablet of Jungle Fungus Clear, which contains nitrofurazone, furazolidone, and potassium dichromate. Unfortunately, I am unable to obtain pure nitrofurazone in my country, but I’ve read that Jungle Fungus Clear is a viable alternative. I’ve continued adding a low dose of aquarium salt to the water as well as feeding my betta kanamycin-medicated food.

Is this the best path forward for my fish?

Housing:
How many gallons is your tank?
My main tank is 10 gal.

Does it have a filter?
My tank has a baffled Aquaclear 30 HOB filter as well as a sponge filter.

Does it have a heater?
I have 50 W Eheim Jager TruTemp heater running in my main tank.

What temperature is your tank?
Usually, I maintain the temp in my tank at 78 degrees F, but I have recently lowered the temp to 75 F to treat the columnaris.

Does your tank have an air stone or other type of aeration?
I am running two Fluval bubblers as well as an air stone.

Does your Betta have tank mates? What kind?
None.

Food:
What food brand do you use?
Generally, I feed my betta a variety of foods, but I am currently feeding my betta TopFin Betta Crumbles medicated with kanamycin.

How often do you feed your Betta? How much?
I usually feed my betta about three pellets or a comparable amount of other food twice daily.

Maintenance:
Before your Betta became ill how often did you perform a water change?
Once weekly. Since my betta fell ill, I've been performing water changes twice daily.

What percentage of water did you change?
About 20% of the water volume.

What is the source of your water?
In the past, I used a 50-50 mix of conditioned tap water and bottled distilled water to reduce the pH and hardness of my tap water. After my betta fell ill, I gradually switched the composition of the water to pure conditioned tap water.

Do you vacuum the substrate or just dip out water?
I vacuum the bottom of my tank whenever I change the water.

What additives do you use other than conditioner? What brand of conditioner?
I always add Seachem Prime conditioner to the replacement water.

Water Parameters:
I haven't tested the pH, GH, KH, and chlorine in the last few days, but these are the values from a week ago:

pH: 7.8
Hardness (GH): 150 ppm
Alkalinity (KH): 80 ppm
Chlorine: 0 ppm

These parameters are from earlier today:

Nitrates: 5 ppm
Ammonia: 0 ppm
Nitrites: 0 ppm

 

Usually, if the betta is eating, there is still hope!

 

I thank you so much, BigManAquatics. Should I stay my treatment course?

Here are photos of my betta that I was unable to post earlier:

 

If showing progress, i would.

 

Hey, I saw the pictures. It seems to be a rosetail betta, if I am correct?
I would keep up with the same treatments, but maybe consider trying API fin&body. It's good for columnaris.
Now, with rosetails, their beauty is both a blessing and a curse. If treatment is not working later, and you have never done anything to cause such illness, don't blame yourself. It could just be due to bad genetics. He is very beautiful btw!!
When my bettas would experience fin rot or other issues too severe to be fixed in their home, I added them into a heated, cycled hospital tank, separate from their normal home. A 1.5 gallon reptile carrier, 80 degrees F, treatments, low light, low current, no substrate, one live plant. Though some have different opinions on what the hospital tank should look like, that's what mine normally are.
It is very good that he is still alert and eating, the only reason you might choose to euthanize, is if he is doing neither of those, and treatment is not helping at all. Just try to remember that bettas don't feel pain, so what he looks like on the inside, he might not feel that way in his mind. Of course, in the end, no one can make that decision for your betta, so if you feel you are doing it in his best interest, then that's a good enough reason.
Hope is still in the valley, so I (we) wish you all my (our) luck!