What Causes Rapid Weight Loss,fatigue And Joint Aches?

My 40 year old daughter has rapid weight loss, is fatigued, her joints ache sometimes she can barely move her arms or legs and has strong heart palpatrations. She takes seizure meds, migraine meds, has a new prescription for magnesium & potassium because the tests show that they were low. She has been to several doctors who say her levels seem to be normal but some days she just can t function. I look at her and she looks like she is anorexic like she was maybe 20 years ago. Within a few weeks she went from 123 lbs to 117 that she weighs now. Some days she is so full of life then the next day she is bed ridden. No one seems to know what to look for or find what is wrong. She is isn t herself anymore and I am very scared. I know she s scared as is her husband & son. What specialists should she see? Her recent doctor told her to get a gall bladder ultra sound, then a colonoscopy. I don t know if this doctor is grasping at straws because she said she didn t know what is wrong.