Thanks for your help and theirs, too. I did notice today that there was a thin black rubber strip that had peeled off the corner seam where he hangs out the most. He seemed to be positioning it to scratch his belly. That could have made it worse, but that doesn't explain his mouth.
And, yes, before the Prazi, I was trying to feed Kanaplex to him. If you think I should go back to that, I can be really careful and be sure to follow the dosing table here on R2R. I know Jay & I were worried about catching him and putting him in QT, but I can certainly try. I would have to be lightning-fast to get him, though.