I had a dog that had an anxiety disorder. Laugh if you want, I would have too. He hid or sometimes he would get obsessive about things and lick or pace.
We treated him with a hormone I got from his vet. It helped. If he got too far out of wack I would give him a lorazepam for dogs.
That's exactly what he acts like... like he's terrified all of the time. Maybe hormones are the answer.