What Causes Stinging Pain Radiating From Left Shoulder To Arm?

Hi Dr. I am having a stinging pain that radiates from left shoulder down the arm. I also have pain that comes and goes in jaw area and leg..all left side. This does not keep me from sleeping but is with me most of the day when I am awake..The only thing I do remember since this started, is waking at night to my left hand being asleep...I tend to sleep with my left arm under my head..this does happen frequently during the middle of night..Had a Physical almost a year ago and heart was fine...did EKG..but wondering if I should go back this week..Having this problem for the last 5-6 days...Thanks in advance for any advice you can give..