I Have pain in my left arm it is mosly while sitting (constant when at computer workstation or when arm bent at desk) or driving is fine at night while sleeping i wake in morning get up sit a table pain starts been to hospital ER heart and BP is fine . Doing work around hose pain goes away lay down 10 mnts pain goes away cant figure this out pain feels mostly mussle (sort of like mussle cramp) Is at time in sholder or whole arm some times numb fingers most pain feels like in arm mussle.