parasite and Colon Cleanse and diet change would be the best way to start..Get her eating more raw fruits and vegetables..or if she's picky, fresh juices and blended drinks. Does she drink soda or artificial sweeteners like Aspartame or splenda? Some people have really weird reactions to that stuff like rashes and pain. Google it.
Other than that..how about looking into homeopathy? Find a professional in your area to help. Homeopathy works by "weird" detailed symptoms; you don't need a diagnosis. But if the problem is dietary you'd still need to start there.