i was thinking breeding tube, initially, but edited my post lol. That doesn't look like his breeding tube. It doesn't appear to be Camallanus, but there is some red in there. I think it looks like a prolapsed anus. It can be fatal if it doesn't heal and is causing blockage. Take a look closer when observing him, and research about Camallanus.
What's your tank temp at? You might want to raise it a few degrees int he 82-85 range and see if that helps. Only thing I can suggest is API General Cure just to prevent and help with anything. I think Jungle Tank Buddies Parasite Clear is the same thing. If it's a prolapsed rectum, it needs to clear on it's own. Only thing you can do is DO NOT feed high protein foods and you probably want to try to feed him as little as you can or fast him.