Sick betta fish needs rescue

I’ve had my betta fish, Buddy for 2.5 years. About a month ago, I noticed he seemed to be lethargic with a loss of appetite and that his fins looked shredded up. After doing some research, I decided that he might have fin rot. I’ve had him in a quarantine tank for a little over 4 weeks (today is Feb 7) with temperatures of 80-82F. The first week, I treated him with API aquarium salt. And fasted him for 5 days. I didn’t see any results so I dug a little deeper in research and decided to treat with one teaspoon of Ich-X + one packet of Maracyn per week with 50% water changes every 7 days. He’s been fed frozen thawed bloodworms or Betta fish food twice a day. After 4 weeks of treatment, his fins seem to be getting worse. All he does is lay in the same spot on the bottom of the tank all day and only goes up to get air & food. His lethargy and fins have only gotten worse since treatment. It is so bad that it looks like there’s mold growing on the tips of his fins. He needs for someone with experience treating illnesses in fish to give him a shot. Unfortunately it’s one of those “if you love him let him go” situations. I don’t know what else to do