That sounds pretty bad. Your best choice right now is probably to take him to the vet, although I can't diagnose what this is. It is best to take your frog to a veterinarian that also accepts amphibians (not just dogs and cats-call before you go to make sure they do specialize in amphibians). I'm so sorry to hear this about your frog. I hope he feels better soon. Hope this helps!

Sanimal