We have an albino Oscar who used to have hole in the head and was sold of cheap in the pet shop as a `needs a good home and TLC`.
He does fine now but where do people get all these ideas about feeding him live foods?
If you are only feeding cichlid pellets it can cause amssive constipation problems.
Try feeding some mussels, cockles, prawns etc. Just break off small pieces because they can be hard to chew.
Also, keep in mind that too many water changes may kill off all the bacteria in the tank.
We once had a major water problem when the water company added a chemical to the water and wouldn`t tell us what it was, we added a poly filter. It`s like a filter sponge and removes any harmful chemicals and things like copper.
Add as much oxygen as you can and make sure there is a good movement on the waters surface.
Best of luck, you obviously love your fish a lot.