Dogs that are not eating will vomit up a mucousy substance with is bile. If she can keep it down, you could try some pepcid. Read about Pepcid dosages and usage information here:
You could give the pepcid along with a drop of pancake or karo syrup on the tongue to help prevent hypoglycemia which you can read about here:
I'm very concerned over why your dog stopped eating and continues not to eat. The pup may have stopped eating due to being in a strange environment. Antibiotics can cause stomach upset as well, so that might explain some of her reluctance to eat. However, a loss of appetite can also be a symptom of parvovirus and if your pup only had one vaccination previously, she would not be protected.
Here is how vaccinations work. Vaccinations are given multiple times due to them not providing a puppy with immunity until the puppy loses its mother's immunity. A pup may lose its mom's immunity at 4 weeks or 10 weeks. To try and protect puppies, shots are given periodically during this time period usually starting at 6-8 weeks and given every 3 weeks to be sure that at least one shot is given after maternal antibodies are no longer in the pup. This is why most Vets do at least one vaccination at or after 12 weeks.
Vaccines typically take 7-10 days to afford immunity. Additionally, shots need to have 3 weeks between them to be effective.
I would take a fecal sample from my puppy into the vet for testing to test for pavo. If by some chance your dog does test positive for Parvo, ask about Tamiflu treatment for Parvo. It is an off label use, but has an extraordinary recover rate when used to treat Parvo IF it is administered in the first 48 hours of symptoms (normally refusal to eat).
Here is a website that discusses vaccinations in detail.
As you can see from the discussion only 40% of puppies 9 weeks of age were able to create their own antibodies in reaction to the vaccination.
Here is a site that discusses Tamiflu as treatment for Parvovirus.
While there are other causes for a dog to have a loss of appetite, diarrhea and vomiting, given that the dog is not protected against parvo, and tamiflu needs to be started early in the process. I'd get her in as soon as possible to be tested.
I hope this information is helpful to you.