It actually sounds to me like a stroke. What did the vet say about what the problem could be. He should have mentioned something about the age of the dog, which is about at the end of it's average lifespan, and recommended something you could do for the dog. Call the vet and ask what he recommends you do, or maybe even take her to another vet. Sometimes the most humane thing to do is put them down. I have had a couple of dogs that had strokes, but they were both willing to eat and drink, even though they didn't get around very well, and often were unable to control their urine or bowels. In both instances, I eventually euthanized due to decline in their condition.