My Sister Has Been Sick For 2 Months With A

My sister has been sick for 2 months with a loss of over 50 pounds......has no appetite......has had many tests and no one can find anything......scans....blood work. Etc......everything has been ruled out from cancer to ulcers. She can maybe eat 1/2 of a banana........her electrolytes have been all over the map. Anything you may suggest??