Hello I am a new yorkie Mommy to a 9 week old puppy and she was doing the same thing the first day or so it seemed like she was eating and not drinking so much. The first day I just put her infront of the water serval times and she would take a few tiny drinks we are on day 5 now and she is doing great! Don't worry I am sure everything fine the pup is just nervous but to be sure I would take her to the vet as you should anyways after getting a puppy
Good luck let us know how things are going.