Just got a puppy, she won't eat anything and has been eating her own poop! Please help!?

I got a Yorki-Poo a few nights ago, since then she hasn't eaten anything. She has been drinking plenty of water. I forced fed her some milk replacements I bought at petsmart which she seemed to like. I was wonderingi if I should maybe try wet dog food. The guy I bought her from gave me a puppy pack which cotained Royal Canin 33 but she won't even go near it. I don't think he was paying attention to her enough to even see if she was eating. He is a breeder so he has a lot of dogs. He did give me medicine for her stomach that was supposed to help her stop vomiting. She did vomit about 7 times yesterday so I started giving her the medicine and she has been fine since then with vomiting. She had diarreah all day yesterday but finally had a solid bowel movement lastnight but then turned around and ate it. I was wondering if there is something I could do to stop that? I basically have no idea what to do. I can't get her into the vet until the 28th so any advice that anyone has would be great