Yesterday I tripped on a plastic shovel and braced myself on a rock wall. I think I heard my shoulder pop out and back into place. I screamed and winced in pain for 20 minutes. After an ER visit last night, I learned that I did not break or dislocate anything. I am still experiencing severe pain on my upper left arm on the outside more toward the shoulder. What can I do? What did I injure? How long will it take to heal? Thank you.