Brandi- (((HUGS))) I admittedly have only followed parts of Lorelei's struggle.
Has your sister sought out a specialist in immune systems disease or maybe infectious disease (according to my doctor friend that is where the brilliant minds go)?
I have a neurologic disorder that was out of whack adn the doctor I was seeing didn't listen to me at all. I was able to self-refer my self to a center at Baylor College of Medicine (the best research center in TX) and finally get support and answers. My husband was misdiagnosed with everything from anxiety problems to Strep virus in his stomach to hepatitis before a surgeon stepped in and got him one of the best gastroenterologists in Austin. Only then was he properly diagnosed with Crohn's disease and given care that has really improved his quality of life.
Lorelei, her sister and parents deserve so much more than "we don't know". (((HUGS and PRAYERS)))

