I'm sorry, I can no help you with your problem. However, just wanted to point something out.
A couple times last week he was sitting on a rock and every so often he would seem to move his stomach in and out and then just hold his mouth open for a couple seconds, he would do that over and over.
This sounds like normal shedding behavior and probably have nothing to do with the frog being ill.

Also, it might help if you specify what kind of frogs you're talking about.