Betta Fish: Bettas find are stringy and falling off

I need help on what else to do for my betta. I currently have him in a hospital tank. It is heated to 80degrews F and has an air bubbler, live plants and a hiding cave. I have tried Maracay Oxy, epsom salt baths, aquarium salt, EM Erythomycin. I just saved him from Swim bladder disease where he was at the top sideways and not eating. It seemed his fins started to fall off then and for the last week or 2 I’ve tried everything to save his fins. I change his water everyday 50%+ and re medicate as instructed. Please advise what I can do.