I think it is time for a trip to the Vet and at least get some blood work done. Could be kidney or liver problems. Could be something as simple as a food change is needed. You might try switching to something like Pro Plan Salmon for Sensitive Stomachs. Always do a gradual food change for a couple of days, mixing her regular food with the new food. Try adding some boiled chicken and rice to her food. You can also give Pepcid a couple of times a day to see if that helps settle her stomach. I've been down this road and, if this has been going on for some time, always start with a visit to the Vet.
I WOULD TAKE TO VET COULD BE PARVO....THAT NEEDS TREATED ASAP!!
How old is she? Does she have past medical issues/problems?
Dogs are pretty good at letting you know when something's wrong, and won't usually show signs of pain or being ill until it's pretty bad (they're fairly stoic in reference to showing signs of being hurt or showing signs of illness).
I would strongly suggest you get to your vet as soon as possible. Not eating or drinking is a bad sign no matter what the breed or age of your animal.
Good luck.
LMNO