It could be also,, she is having pain,, much like babies,,, Try freezing a wet cloth with garlic sprinkled on it,, also icecubed chicken broth is a nice treat,,,

Doing the leash thing in bed is a good suggestion too if youre wanting your pups to sleep with you....

Good for you for doing the rescue thing,,, it could be the pup had a rough beginning you dont know about and is just anxious,, be patient,, I bet it will end eventually,,,,,,