I fell in aug. Of last year and sprain my arm, there is still inflammation in my collarbone area along with severe back pain. The ER doc. Said it's oa?

It will be. If you are not able to restore normal motion to the shoulder. See a do who does manipulation to make sure that the ribs are moving normally. Then there are exercises that you can do to help you restore normal functional relationships between your ribs, shoulder blade and collar bone. Academyofosteopathy.Com has a doctor finder function to help you find someone near you.
Osteoarthritis. Oa or osteoarthritis is degeneration (wear and tear) of the joint cartilage between two bones. Falls or small accidents can irritate joints easier when there is already degeneration in the joint.