Sounds like the horse is adjusting to its' new place. This can be really stressful to a horse. I assume she is not along at your place? Other horses with her , or at least within sight?
She is exhibiting classic barn sour behavior. The barn is security, and leaving the barn is scary , and means work. I think her chewing the bit a lot is also a sign of anxiety.
Is there anyone there with a bit more experience with theses sort of problems that can help you work her through this?
Do a search for threads on "barn sour" horses for more detailed advice on how to deal with this behavior. Good luck adn welcome to the forum.