It sounds like she's sick. Anytime a dog's behavior changes in any way, it's time for a visit with the vet. Puppies are very vulnerable and can get sick and go downhill very fast. Shaking is a sign that your dog is in some kind of pain. All the other symptoms you described are Not Normal. Emergency Vets are open 24/7 and always's available. If she was my puppy, I would take her to an Emergency Vet tonight! Is it possible, that she could have gotten into something Toxic, when you were not looking?