While digging out an igloo yesterday I heard a popping noise in my left arm and I was unable to move my arm without experiencing severe spastic pain which started in the one spot and spread pain all along the arm. (it took me nearly 10 mintues to back out of the igloo due to the fact that I could not move without my arm hurting so bad that my entire body would seize up. After I was back in the house I was unable to lower the arm flat to my side. Several times when I was forced to move around my arm would spasm and I felt almost as if I was going into shock. My breathing would become very shallow and labored and I would have to stand completely still for several moments until the pain subsided. This lasted for a little over two hours with the spasms becoming more frequent, but less intense, and shorter lived. While sitting at the table I made a slight movement to reach for something with my right arm and I heard another pop, same location, and just as quickly as the immobilization started, it went away with only a small amount of soreness as a result of the experience. Similar occurrences to this have happened with the other arm, but never quite as severe or long lasting. It is the same spot on both arms. What I believe is a bicep, inner arm, aprox 6 inches down from the shoulder blade. The popping is always the first indicator and it feels as though a wide sharp object, more like a javelin than knife, is pressing into that one spot. No one thing seems to trigger the experience, and minor occurrences last only a moment after which I can resume whatever I was doing without anymore trouble. While these episodes are always painful they are not overly long lived (rarely do they last more than half an hour) and don't seem to have any lasting effect on my life, I would like any ideas as to what might be causing them and if there is a way I can stop them from happening again.