I am not sure, but I may have a pinched nerve in my neck that is causing severe headaches. 2 years ago I was hit by a motorcycle while riding my bicycle (he didn't know how to drive it), and my left humerus was broken. I had surgery and a scalene shot to reduce the pain. Would the muscles being shortened or the nerves around the arm or shoulder/neck somehow be a cause of these headaches? The headaches are more like a toothache than a normal headache.