Great advice, friendly people, and lots of frogs!
I don't claim to be any kind of expert on amphibian illnesses but the symptoms you describe are a pretty good match with Chytridiomycosis. It's caused by a fungus called Chytrid which is a major contributor to the current decline of amphibian populations around the world. Chytridiomycosis can be cured but it's extremely difficult and survival rates are still very low. Do a search for "Chytridiomycosis cure" and research it. Good luck!