Sick daughter goes undiagnosed

My 26 year old daughter has had on going health problems since her teens. She has been from doctor to doctor and no once can seem to pinpoint what is wrong with her. She weights 89 lbs, can't gain weight, has chronic pain in her abdominal area and a small mass that can be felt. She has had 4 MRI's which found nothing. She lives in Arizona and was in the Scottsdale Mayo ER, they thought it was an ovary or endometriosis and they did an ultrasound, blood work and pelvic exam. Found nothing, sent her home but told her to come back if things got worse. They never get better. I wish they would have looked further to see what the problem really is if it isn't female issues. She is so slim you can feel there is something going on, a mass. She also gets chronic inflammation in her rib cage on one side, on and off. No one can explain that either. Her blood work shows she produces very little progesterone. No one really has done anything to address that. Her diet is very limited because she gets ill very easily. She gets night sweats that soak her sheets just about daily. She runs low grade fevers frequently. She has had many tests done over the years, and while things may come back "slightly" off, no one has a diagnosis or explanation for why she is chronically sick. The chronic pain is affecting her mental state as well. She can barely function enough to keep a part time job. Her income level is low so she could never pay out of pocket to get diagnosed by Mayo. Her government insurance policy that she pays for doesn't want to approve many tests or specialists. Even when they do, they are mediocre and all they want to do is give her pain meds and anti nausea. She does not take the pain meds and the anti nausea just provides a bit of relief. She needs a diagnosis, not meds that cover up symptoms. What is causing all of this? I wish she could afford to go to Mayo to at least get a diagnosis. She is deteriorating and no one helps her. We do not know what to do. I am her mother and I live in Wisconsin and do what I can to help her keep afloat. At 89 lbs she is frail and dragging herself through her days not living life. I am scared for her. I wish I could find her some help.