I agree. She needs a bile acid test. Did you know that Yorkies are 36 times more likely to have a liver shunt than all other breeds combined? If she didn't come from a reputable breeder who screens for liver disease, there is a good chance that this is what your puppy has.
Portosystemic Shunts FAQ
How old is she? Bile acids tests can't be done until she is 20 weeks old.
I pray you got a health guarantee with this puppy.