I'm so sorry she's not getting better. By any chance have they done any autoimmune testing? I did a lot of research after what happened with my Tyson and came to realize that he most likely had an autoimmune disease, possibly systemic lupus. It seems that with all the normal testing and even though I kept saying there was something else after what was found and corrected no one thought about an autoimmune issue. I did consult with a holistic vet after and came to this after someone told me about the possibility, but it really sucks knowing and wondering after. I was told that they just don't think about the possibility of autoimmunne and that may be true as specialists and multiple vets said nothing showed yet he was sick off and on.
I really hope things turn around and they can find a way to help her, sending you guys prayers and hugs.