Another vote here for getting her to the vet's. I wouldn't have been too worried about the non-eating part but if she can't keep things down and isn't drinking that is a red flag to me.

I once dogsat for a neighbor's dog (in my home) who didn't eat for the first three days they were gone. She used to sit at the front door and wait for them to come home. She was drinking, though, and wasn't sick but even so I was so worried.

I agree that since this is sort of a "senior" dog she may not have the reserves a young pup might have to draw on, and this could be serious. Please keep us posted.