What Causes Shooting And Sharp Pain In The Upper Right Arm?

I have had pain in my upper right arm for about 3 weeks now. Usually dull aching but sometimes shooting and sharp pain. Within the past week the pain has proceeded into my right shoulder the same way. I actually have several area on my upper arm and shoulder which are sore to the touch now also. Now last night I was awake all night since the pain has gone into the right side of my neck. This pain is even more severe going from moderate to severe if I attempt to extend or manipulate my arm certain ways. It is quickly becoming intolerable. I had had no accident or trauma to any of the areas mentioned. What might this be?