My yellow eye kole tang which I've had for about a month has suddenly become sick. His mouth seems to be stuck open where he can't get any food in or pick the algae off the live rock. He also went from being very active in the tank to hiding and not swimming very well with the currents in the tank. I don't notice any white spots. Has anyone seen anything like what I've described? Attached is a photo trying to show how his mouth is stuck open.