Wow, so much product being recommended. I agree with Jeff that simple is often best. With that in mind, it seems you let the ammonia get out of control. Do you have your own test kit? You should, you have too much at stake to rely on sporadic tests at Petsmartco. Many times, they are using outdated strips that are inaccurate. And then their answer is to sell you more product, neutral regulator seems to be one of their favorites.
In my opinion a minimal test kit for this area, with pretty good water, is ammonia, nitrites, and nitrates. PH might be important when setting up, but I seldom need it after that. I believe the liquid tests are more accurate and more cost effective, but both types have expiration dates on them. Heed these dates - they don't last forever. If you do use the strips, make sure to open the container with dry hands, and then close it tightly. Moisture degrades them.
To heal your fish from their recent ammonia stress, I would keep doing frequent water changes and extra aeration, regular testing to be sure you are changing enough water, less food like you said, perhaps some salt, and keep a close eye on them. The clout would be for a bacterial infection, I think. That might be appropriate if they get worse, but it might be unneeded with the above.
And like Betty said, you need to try to determine why the ammonia got so high. Perhaps the tank is overstocked - it is easy to do, especially when fish are growing.
Hope your fish are better soon.
