I have a rosie red that is about 9 months old. Last night its eyes bugged out, does anyone have any ideas why?

We have had this fish for 9 months and no problems. It lives in a community tank with a mix of other fish (no new fish lately). None of the other fish seem to be having a problem, but the rosie red's eyes have not went back down to normal size. An ideas as to what may be causing this problem?