Thyroid? I'd ask the vet if it might have anything to do with a thyroid problem, which I would doubt, if your pup is so young, but maybe.
Properly trained, a man can be dog's best friend.
"If you love wealth better than liberty, the tranquility of servitude better than the animating contest of freedom, go home from us in peace. We ask not your counsels or arms. Crouch down and lick the hands which feed you. May your chains set lightly upon you and may posterity forget that ye were our countrymen." -- Samuel Adams 1776