Oh, no! If you can't diagnose it immediately, stop feeding except for high-fiber foods. My Adonis died this way, and it ended up being an internal fluke-like infestation. Agree on poo check. Also advising tracking down Prazi-Pro if poo is suspect. Soak quickly-eaten foods in Prazi-pro and dose daily if it is worms. If it is not worms, but potentially bloat, raise temp and try a quick epsom salt bath. Sadly, I was not able to save my own fish, as I did not know about Prazi-Pro back then. Perhaps someone with success in this challenge would be more helpful, but there's what I would try. Best of luck.