There are many reasons a dog will not eat. Often loss of appetite is a sign of nausea or pain. The source of the nausea can be primarily related to the gastrointestinal tract or can be secondary to another underlying illness. The gut is the stress organ in dogs. It is good that your dog is drinking and not vomiting. If he does not start eating in the next 24 hours or develops other signs he needs to be examined by a veterinarian.
My dog is a bassett hound, and I learned when they are in pain! They shake quiver and will not eat the best thing and only thing I would do if I we're you? Is to take her to a vet poor Lil girl, it could be a number of things but do'nt wait until it's to late! They can't tell you what is wrong, but they so depend on you take care of her! And I do know when they drink a lot of water it could be a kidney infection or bladder thing going on. Pinch her skin and pull it up gently and if it stays then she is dehydrated. Hope she is ok!
Have the kidney levels checked