What Causes Pain And Body Tremors That Begin With The Right Hand?

My brother, a 60 yr old white male, has been very sick. HIs pain level is so bad he is taking morphine every 12 hrs and oxycodone every 4 hrs. He has had MRS of the brain and spine. Back surgery was not recommended. He lost 70 lbs (possibly related to a gall bladder problem that took time for the Drs to Dx) Very weak almost wheel chair bound. Hands and entire body will shake. Saw many neurologist and recently is being check at U. of Pittsburgh. they ruled of MS and Parkinsons. They are thinking possible autoimmune disease Do u know what would cause severe pain, and shaking. It starts right hand, head r. leg, left side.