A thing to remember about the the ammo-lock solution is that, though it converts ammonia to a harmless solution, it also may affect the readings of your ammonia level. in other words if you use it, then test it, the tests will still indicate there is ammonia in your tank.
I would use a solution to dissapate the ammonia in this type of emmergency to help out your fish temporarily. However, I would get down to the bottom of why your ammonia levels which are increasing instead of decreasing.
Some suggestions and questions for you:
Is your tank cycling? It is natural for the ammonia level to spike, just keep doing the water changes as it cycles. I do 50% a day. I am currently cycling my tank. Right now even after I change my tank my nitrates are still the same, I believe...because it is still cycling.
Yours could be doing a mini cycle? Did you add any more fish during the cycle if you are cycling? If this is true, then you might have to redo the cycle!
How much and how often do you change your water?
Is your tank overstocked? rule with small fish is 1 inch of body of the fish (excluding the tail) per gallon. However, sometimes according to activity level of the fish, this is not true. I am not in anyway experienced with large fish and stocking them though.
What kind of fish do you have? If you are cycling your tank you should use hardy fish...but usually try to do a fishless cycle which would be better for fish. Dwarf Gouramis have been known to have the iridovirus which have similar symptoms you are explaining and has nothing to do with the owner. They become listless and turn dark then die. Do you have these fish? It might be a possibility?
Do you overfeed your fish? The fish's stomach is about as big as it's eye in most cases so only a couple flakes of fish would suffice. If you overfeed the ammonia level will rise.
Is there any other kind of stress the fish would be experiencing, which would lower their immune system and make them more susceptible to illness such as a tank being in a loud area where children are playing? High temperature, low temperature?
I like to use freshwater aquarium salt as a preventative for fish illness, and so far it has worked well for my livebearers, though I am not sure what fish you have and how it affects them.
Also, I learned from Chief Waterchanger on here that adding 1 teaspoon to 1 tablespoon of garlic per 10g may help fish diseases. If you want to ask him about it I'm sure he will be happy to help! Also if you add salt to the water sometimes it helps with
ICH. I don't know the exact formula, but there is an article on this site I came across that might be of interest to you if you search the website...actually I believe it was in a forum in here...I saw it on the top of my screen today and clicked on it but didn't read it thoroughly. I am a beginner like you, but I hope this helps! Good luck and let me know how it goes! Anyone else here that is an expert is very welcome to criticize my advice. So please chime in! Thanks!
Oh wow, before I even got to write this in, other people wrote in haha!