This clownfish went through a 30-day QT with light medication. It’s been 10 days since he(or she) was added to the display and as of last night he hasn’t been moving much. He is opening and closing his mouth rapidly, and there is a singular white spot on his chin. He also had little dents in his head. 0 ammonia, nitrates, or nitrates (which I do need to bump up) and every other fish, including his mate, is doing good. Same with corals. He is eating properly. Any idea what this could be and how to treat it?