About 4 weeks I began having pain in my shoulder, in the top front and shoulder blade area that feels like I m being repeatedly stabbed with occasional burning sensation. This feeling does not stop. I wakes me from sleep. I cannot use my arm well to work (I am in construction) and have had to perform many tasks with my other hand/arm. I am having muscle spasms all the way down my arm, past my elbow and in my chest. I thought it was a tight muscle, like a knot and would go away. The pain has increased over the past 4 weeks and is unbearable. What could this be?