Welcome to Tropical Fish Keeping forum.
First and most important, stop adding chemicals. There is no substitute for regular maintenance and proper stocking levels. Some of those chemical substances will interact with others and create even more problems. And some, like the Easy Balance Plus, are harmful in themselves because they interfere with the natural bacteria--and by bacteria here I am not referring to the nitrification bacteria but the host of other bacteria that breaks down organics.
So, to get things back on track. Regular but smaller partial water changes are the only way to go. Use nothing but a good water conditioner.
Leave th pH alone. Those fish are soft acidic water fish and will be fine in a pH in the 6's. Fluctuating pH is very stressful and can cause permanent and irreversible internal damage to the fish.
Are there any live plants? These would help immeasurably. If the pH remains below 7, ammonia will change to ammonium which is basically harmless. The nitrite is not however, and any above zero is trouble. Plants would avoid nitrite, as they grab the ammonia/ammonium first. Even something as simple as floating plants will achieve wonders.
For more detail on the above, you can read about bacteria here:
The fish stocking has issues, but lets get the tank back in shape first.