Betta fin and eye concern

Hello we rescued this betta from a school aquarium last year and he’s always been a little weak since then. When we rescued him his scales were like a pinecone and had dropsy. We cured him with api general cure and was good for plenty of months. Recently he’s been having some fin issues and his eyes look a little weird to me but I’m not sure if they’ve always been like this. He spends much of his time at the bottom of the tank and swims around only to get food. I’m not sure if this is fin rot and Popeye? He’s in an aqueon 5.5 gallon, and gets a 30% weekly water change. Water parameters are always 0 for ammonia, nitrite and nitrate (sometimes 5 for nitrate) I use the api master liquid test kit. Let me know if you know what’s wrong with him?