Little Miss, please try to find another vet willing to have a look at your girl sooner than your scheduled vet appointment.You can try some boiled chicken and rice, steamed veggies.
In the meantime, feel free to contact me. I know of many reputable breeders on the East Coast of Canada who would certainly supply you with information on health issues, care, and suppliers of a Quality Healthy Food for your Yorkie who may deliver to your area on the Rock!
Best Wishes