My dog is scooting an the carpet, it looks like he is trying to itch his butt....what is he doing?

Well this sounds like a common problem, and something you will have to go see a vet for. Dogs have two small glands inside their anus that build up liquid, usually the animal expresses the liquid on their own but it is common that the dog can not express their glands. This causes discomfort thus they scoot trying to relieve the discomfort. If not treated, it can lead to further proplems including infection. A veterinarian can help you with this problem.