Describe exactly what you're seeing? Swelling, redness, etc? Can you post a picture of the fish?
Water parameters?
Describe your set-up; tank size, other fish, live rock?
If you're feeding fresh water feeders, you're slowly killing the trigger. Change up the diet to chopped pieces of shrimp, scallop, squidd, silversides, plankton, and other crustacean flesh. Feeders will build up fat deposits on the fishes vital organs and cause numerous health problems/premature death.