What I had to do with my tank to clean it (I had a cork background siliconed to the glass) was to get a hydrogen peroxide based cleaner (can't remember the name- Accel?) and then use a professional steamer on it.

Also, when you talk to the vet on Monday, ask them about reptilecity.com. Chances are, they probably know about them if they are relatively local to you. Unfortunately, at least in my experience (and the other members here can correct me- they have much more experience with this than I do), once you receive the frog, walk out the door, anything to remove it from the dealer or pet store's hands, there is no guarantee with a frog. A DOA with shipping that you have to prove you received the frog and it didn't sit in the box anywhere is about the only guarantee out there. I would call first thing in the morning, because they will most likely want to see the frog and evaluate it, see if there is anything else they can find or do, etc. If it is a bit of a drive, calling first thing will give you a better chance of getting an appointment at a time that is most convenient for you. Be sure to bring the deceased frog with you. Bring pictures of your vivarium as it was to show them as well. If you can get any stool that is less than 24 hours old, bring it along as well. You can put any samples you get between now and then in a baggie in the fridge (I know, that is more than 24 hours, but you do what you can with what you have).

Good luck and I wish the best for you and your frog. I hope you are able to figure out what is wrong and get him cared for.