when i had that pain,it was diognosed as costrcondritis cartilage tearing from the bone and it is pain like i never felt,please get a x-ray immediatly, mine turned out to be a broken rib bouncing around like a dagger ,thats quoting the doc in the er,trust me you will know i slid of a chair screaming an im pretty tough,i hope its not anything for your sake and well being ,please take my word for it get it tended to baby it ,sleep with a pillow under your armpit,bells an whistles went of when i read your question ,good luck an god bless