She Won't Eat

So I'm really worried about the puppy.  She seems to be getting better as far as getting used to me and the house, she's playing and running around, but she's not eating.  She didn't eat Friday, she didn't eat Saturday, and she only took a couple of bites this morning.  She hasn't eaten anything since then.  She is drinking water, so that's something, but I'm still worried.  I'm taking her to the vet tomorrow for a puppy check, so I'll talk to him about it tomorrow.