I have a purple tang that has white spots on it(i.e. stomach area).:sick: Even the lips are white. Not ick. Also, it looks like it has lock jaw. It's gills are still moving, however, it does not open it's mouth. I have not seen him/her eat in several weeks. Will not eat anything(i.e. mysis, nori). It continues to swim around. It look miserable. I thinking about taking it out of it's misery. All other fish are okay. Water parms good. Just did a water change with H2O. It's been in the tank for about 3 years. Any thoughts?