Strange protrusion on one of my fish! Any input?

First topic message reminder :

Hey, All! I have a Pseudotropheus sp. "Williamsi North" juvie that is about one and a half inches long. All of a sudden, he has a large bulge in his abdominal area on the left side. It's almost blocked looking and not really rounded. I don't think it's bloat because he's eating fine acting normally, and has good color. What could this be? A tumor or something, maybe?

I can't seem to get a good photo of it.

We just got a williamsi! :) I would try an antiparasitic. The epsom bath wouldn't hurt either, just don't stress him out too much. Keep us posted, hope it turns out okay :)

Thanks!