I just did a quick google search and everything you've tested for is listed as a cause, as well as OCD. They recommend bitter sprays...which you've tried. And behavior modification but you would have to keep her near you at all time to stop the behavior and redirect. With her other issues you've had, I wonder if the Stress Free might also help those as those are related to fear and anxiety also.
~The strength of one's opinion should not exceed their knowledge on the matter~