My chuihuahua is drinking water but not eating she has a spaced out look and doesn't play. Iu think she might have eaten an a acorn in the yard she eats anything,until now she is just not the same.She will walk around but not for long then goes back to lay down.I have other dogs and they are fine that's what makes me think she has ssomething in her stomach lining and nit parvo but not sure.

She could have a bowel obstruction, if its something she has eaten, so the only advice I can give is a trip to the vet to determine what it is.

Tick

Agreed, there isn't anything you can do from home.
Your vet will most likely try to palpate and feel for any lumps and bumps in the stomach and if that fails they will do an x-ray.

Not eating can be a symptom of so many things though, it might not even be a bowel obstruction.
Parvo is usually accompanied by vomiting and diarrhea although symptoms vary between dogs.