Welcome to YT.
You posted just fine. I'm sorry you are having this problem. Do you know the background of this little girl? That would probably help some people who might be able to help you.
Was the groomer the owner or was she selling her for someone else?
Was she previously used for breeding?
Is she housebroken?
Whatever her situation prior to living with you, it sounds like she is very scared and will take a lot of patience and time.