I have been diagnosed with osteoarthris in my left shoulder joint.  But, right now I woke up with pain in my chest shoulder area radianting under my left shoulder armpit.  I am scheduled for an MRI next week, but what could be causing this pain.  I hurt so bad Im crying.
Hi, Given he history of O.A. shoulder and now radiating pain to arm pit and in chest it indicates that a nerve has been impinged at your armpit level. Things will be pretty clear once you are done with MRI. Until your next doctor appointment do apply hot pack and avoid lifting heavy weight and doing overhead activity and while sleeping avoid sleeping over involved shoulder. It may aggravate the pain and discomfort. Hope you will find the answer useful. Let me know if I can assist you further.