It sounds like your new baby has been through a lot. I fostered a dog for a while that did the shake thing and I took him to the vet to find out why and she said a lot of animals that go through some form of trauma often shake out of comfort. But it's not comforting to you! My little Leah now dose it as well (Bad habits spread fast) mainly if we are driving in the city where there is a lot of loud noises. But the foster dog is with my brother and is doing really well not shaking at everything now!
