You can also drop pieces of epsom salt in and see if you can get him to eat a piece. Sometimes this will help.
Sometimes swim bladder problems always stay with the fish and he will have to be on a special diet of live/frozen foods and chopped spinach, peas , oranges etc., for the rest of his life.
You say he swells up and this also could be a symptom of Dropsy. Sometimes Dropsy is caused by a bacterial infection. Put your fish in his hospital tank and add 1 TBS of salt per 5 gallons.
Feed a medicated fish food. You can get antibiotic fish food at your local pet store.
One other treatment that you might try is to put 250 mg of Furanace in one gallon of water and put your fish in this for one hour. Then put him back in his hospital tank. Repeat this for 2 more days.
Good luck and please keep us posted!