Welcome to YT.
Congratulations on your new little girl.
Do you know any more history on this little girl besides being owned by a groomer. Is sure sounds like she was always left inside a cage/crate and not properly socialized.
I would think if the owner had a grooming shop her pup would love to be around people and not act the way that you are describing. My groomers dogs are very people friendly and think everyone is there to visit with them.
Here is a link to helping to socialize a puppymill rescue. Although it titled puppy mill there is plenty of really great advice to help with what is going on with her. If you need any more help please just ask
http://www.yorkietalk.com/forums/yor...ll-rescue.html