I think you should get a DVM, Chiro to check her out. She is probably in
pain, either a rotated illia (hip bone) or a sacrum. A chiro could put it in
and would be more sensitive to the possibility of this kind of issue.
There is some soft tissue release that you could do to help her a bit, but
you need to rule ou the pelvis to make any progress.
Let me know if you want me to describe the soft tissue stuff. AND you will
sign a waiver for any damage you may get. Just kidding.