My dog is weak and not herself she just lays around and won't eat but will drink water and when she does she throw it back up

Dog is sick and weak will drink water then throw up and won't eat does he have parvo?

Does she have diarrhea? Is it bloody? Is she eating?

Sounds more like a blockage to me. But sadly we can only guess, we can't diagnose.

What did the vet say? What tests did the vet do? Was parvo tested for? Why is your vet unsure about a diagnosis? What other tests were done while at the vet?

Vomiting, diarrhea, uninterested in food. Can have blood in the stool, but not always. Sometimes, they can even have a temperature, which is never a good thing considering that the infection of bacteria is starting to set in.

Parvo is very contagious and deadly. This dog needs medical attention now.