[QuickSilver]

He's very cute!

I would definitely have him checked for the things other posters have mentioned. However, I wanted to note that shaking can simply be a sign of anxiety. The fact that he jumps out of his skin when you wake him up is also a sign of high reactivity (though it could also be a sign of pain). Exceptional noise sensitivity is another sign, though most dogs dislike fire alarms.

Thor sometimes shakes when he gets very excited. He belonged to someone else when I first met him, and he shoke pretty frequently. I think it is because he is a timid dog, and he needs a lot of exercise to keep him reasonably relaxed (just like a stressed person).

I didn't really see him shaking in the video? What I mainly saw was that the camera made him uncomfortable (again, very common). The exaggerated yawning and lip licking are appeasement signals.