Help! My bubble eye goldfish popped his bubble?

My beloved Bubble eye goldfish had really large eye sacs, he's been doing great the whole time I've had him, but when I came home from work this evening I saw a huge wad of tissue hanging down from what used to be his bubble. So far his appetite is normal, he's actively swimming, but what should I do to help him heal? I'm heart sick and really appreciate any helpful answers