There is a swim bladder treatment using epsom salt you could try. I have a sunshine peacock with the opposite problem. he eats and swims, but then falls to the gravel like a rock.
Treatment is 1 gallon of water and 1 table spoon of epsom salt. make sure it is fully disolved. The fish is placed in it for 10 minutes. Phase 2 is 1 gallon of water and 1/2 teaspoon of epsom salt. The fish is placed in it for 5 minutes. need to watch the fish the whole time for shock.
Next time I try this I will do the 1/2 teaspoon phase before and after the 1 tablespoon phase. Makes sense go ease the fish in and out of the treatment.
In my case, the fish isnt fully recovered but he is much better. at one point he could only lay on his side. Now he is swimming but still cant float without sinking. if he never recovers he will just be a permanent resident of the 2g tank he is currently lounging in.