It does sound like your frog is bloated. It could be chtridomycosis, especially since the skin seems to be affected and it's staying in the water all the time. Do you have a vet that could treat frogs?

I don't know much about pyxis, hopefully someone who knows more could give better advice.

Also is your frog eating? And if it stopped, when did it stop eating? Are the legs red? Are there any broken blood vessels showing?