take her to back to the vets ASAP!!! My Millie went like that when she was about 6 months old and i was told if i had left her another hour to go to the vets i would have lost her. Turns out she had a virus that a few dogs in my area had that couldnt be vaccinated against. All the other dogs just had upset stomachs and were out of sorts but as Millie was so small and young, it made her really ill. The vet gave her some injections, gave her some pills and medicine to go home with and some special bland food and she perked up a few hours later. I was so lucky i came home from work when i did and found her otherwise she wouldnt be here today. Try and get her to drink as much water as you can or puppy milk, anything to get nutrients into her.
You know what your furbaby is like and if you feel she isnt well, take her to a few different vets until one knows how to help. I would go to the ends of the earth for my furbaby and wouldnt stop at anything to make her well.
I hope and pray that your little'en gets better soon x x x
__________________ *  *    Millie & Mylo   *  * |