Usually, scraping and flashing means some sort of flukes. They get in the gills, the eyes, and under the scales. They are very irritating to the fish and he is trying to scrape them off. If you don't get them off, he will stop eating and die. I would get him out and do a 2 hr bath in a Para-guard solution. If he has flukes, that may get them off. If you can QT him for a few weeks, you can observe and treat with something different if you identify a different disease. If you can get him to a QT tank, I would give him a couple of days break after the Para-guard bath and them dose the QT with Prazi-pro for a week.
If he has ick, then do the TTM on him. That works well. Not sure what your tank is like but I don't recommend dosing your display with Para-guard. I can kill corals (if you have a reef). Also the Prazi-pro can kill feather dusters and other worms in your tank. A Royal gamma can easily be treated in a 10g tank.