Hello, I'm Dr Gary. I've been practicing veterinary medicine since 2007. I look forward to helping with your questions/ concerns.
If she is that old and just now got her puppy vaccines, I would really worry about Parvo
Virus. Parvo is one of the viruses that the distemper
vaccine protects against. If she was exposed to Parvo and then got vaccinated, it will make the infection even worse. We can see vomiting, diarrhea, lethargy and decreased appetite. Eventually it is fatal if un-treated.
I would get her to a vet where they can Parvo test her. If positive, then they will likely hospitalize her for 3-5 days on IV fluids and IV antibiotics. If negative, then they'll probably get some fluids in under her skin and anti-nausea meds. They'll then likely send her home on some Pepcid and an antibiotic (Metronidazole) to get the vomiting/ diarrhea under control.
I would try to get some canned food
and water or Gatorade into her every 2-4 hours until you get her seen.
I hope this helps, let me know if you have any other questions.