First off never believe what the pet store people tell ya. I swear some of those folks have never read an animal caresheet in their life! The pink belly could be an indicator for an upcoming shed but it could also be the early stages of a burn. You need to monitor those heating devices closely. Do you have a digital thermometer? They have some really inexpensive ones at Walmart in the outdoor thermometer section. Get one that monitors two temps and humidity!! They're awesome.

As for the jelly stuff.... Not too sure about that. If you haven't had the animal checked by a vet I'd do that. It's always good to know that they don't have any internal parasites.