I always sleep on my right side, and my left arm goes numb. it swells and is very painful even after the numbness fades. what is wrong?

W/out exam...: cannot directly say. ANd, obviously a circulatory issue would cause swelling and inadequate circulation makes the nerves feel sick resulting in pins/needles/numbness/pain often with some changes in color Thoracic outlet, subclavian steal something in the circulation in the armpit (prev. trauma/surgery or congenital malformation) could all do this.

TOS: Possible Thorasic Outlet Syndrome on the Left. Have this checked out by Vascular Surgeon