there is a disorder that labs or high energy dogs get. its from lack of mental and physical challenge and excercise. My lab had the same symtoms for a while and I really had to work him hard, let him sleep in our room so I could listen for him to start licking, and spend a good bit more time with him to get him to stop. Vet said sometimes you can sometimes you cant. It's called acute---- something. Your Vet should know what it is... if they don't get a new Vet.