shoulder injury

I am sure this has been asked. If you can help to point previous discussion. A friend, a bouldering coach, does not use Internet and is a Japanese. He has a  shoulder pain. He can lift his arm from the front but not from the back. I think it is a shoulder dislocation. If you happen to be in New York city, you will run into Yuki, the bouldering coast in Central Park. We need home remedy and exercise routines.