72 is a little on the cool side, but I doubt that was the cause of your current problems. Generally when a frog goes off it's food for a long period of time it is in response to a septicemic infection (usually bacterial). It sounds like your vet doesn't have much amphibian experience or they would have picked up on a problem like this. The treatment is usually a course of antibiotics by injection. Now I must add that I am not a vet, nor can I give you an absolute diagnosis over the Internet, but what you're describing is a familiar scenario. Treating the disease is often not enough - the frog probably got sick because of some stress it suffers on an on-going basis. This could be almost anything, but a 15 degree temperature drop every day might be it (just guessing).