One can not judge what you are doing wrong if we dont know what exactly you are doing now can we...: )

First...the bloat dont sound good, I would quarantine him for his own sake in a another bare tank with a piece of pvc or somathing for him to hide in so the water can be changed more offten and left a bit more clean.

Second, we need a idea of what your setup is like, IE...size, decor, temps, a few more that may help us,.. How long ago you purchased them, and where?

pics would help as well.