I would say a "red" belly is not a good thing, but a pink belly could be totally diffrent. My husband and I just joined a local herp club and last week we were learning about scale rot. I'm not saying that what your's has, but one of the symtoms was having a red (almost like a burn) belly. I would try soaking a couple of times and if it doesn't get better, or if it gets worse, you may want to see your vet.