I wish I could help more, but I'm not sure what to advise you to treat him with. I will say it does sound like internal parasites to me though. If you post his symptoms in the general care section I'm sure you will get some helpful advice.
The only meds I have treated my fish with through the years is Methylene Blue, and it has helped with several different problems, from fin rot to parisites...It's only about $2 at Wal-Mart. But again, I would ask around for other opinions about what will work best with his symtoms.
Good luck with him!