Hi Judi,
I'm sorry your baby isn't feeling well
Has the vet done any barium series xrays? There could be an intestinal blockage from something that she chewed or something. I just lost my 3 year old baby Starr to complications of surgery to remove a blockage, and she had the same symptoms going on.
Please get a second opinion at another vet if you can. Starr's vet didn't find anything wrong with her either, for 4 whole days. In the meantime,she lost almost a whole pound despite the fluids and nutrical. Please don't wait!