What Causes Pain Below Armpit Which Moves Across To Chest?

I started with a strange stabbing pain in the left side just about a hand below my armpit which moves across to the chest when I move my left arm in towards my chest. it also worsens and feels like I am being stabbed if I start lifting my arm up towards the back of my head. it wakes me at night and now it feels like my upper rib cage and back are in a spasm. There is no pain if I breathe deeply or cough it is a lingering pain and only increases when I move the arm in and up ?