The part that would bother me the most, snaping at the groomer, I have never had this kind of change in personality, but hearing others that have had such problems, the consensus was to see the vet to rule out any extenuation of a medical problem before you go the behaviorst route. Thats fairly long time to go with this change kind of change in behavior. A good dog does not just turn bad without a legitimate reason. Just wondering if the groomer may have intimidated your dog at a previous visit. Assuming that is the only time your little guy is ever out of your direct observance?