Help my dog won’t eat

Hello I have a four month old, red nose, pitbull, who’s full of energy as of Sunday around 4 AM. She came back inside and wasn’t feeling herself. She has not been able to eat anything and is constantly throwing up. She looks very weak. Doesn’t wanna do anything she does have her first of Parvo shots she’s been drinking Pedialyte and water and hasn’t been really moving frequently like she usually does. Today was the first day she pooped and it was very watery. Is there anything I can do and if she does have parvo is there anything else I can do

Hello - yes.  Whatever's wrong with your dog, there may be a chance that they are vomiting / have already lost more water than they are taking in.  This would make them dehydrated very quickly and if this were to be the case, then they might need to be on a drip, whatever happens to be causing the symptoms.  Please therefore contact your emergency vet, or your regular vet if they're open, as a matter of urgency.  Possibilities at this stage may be wide ranging, from kidney disease to liver disease to toxicity to pyometra to cancer to pancreatitis to diabetes to a foreign body.  Anything causing dehydration and systemic illness may be an emergency.  Your vets' office or OOH emergency vet should triage the case and advise.