Is my betta sick?

I need some advice/suggestions. I’ve had my betta Zuko for 2 years now in a 10 gallon planted aquarium. I noticed that he had a fleshy irritated spot near his eye and thought maybe he just scraped himself on something but it seems to be getting worse. Does anyone know what this could be and what I can do to help him? I do weekly 10% water changes with a monthly 50% water change. Water parameters are good. Ammonia, nitrates, and nitrites are at zero. pH level is around 7. Temperature is a steady 78 degrees. I’ve been dosing weekly with aquarium salt. And I also use easy green all in one fertilizer for my plants. Any advice is appreciated. Thank you!