Keep your shoulder as mobile as possible. Most shoulder pain occurs when the shoulder becomes stiff and restricted.
Frozen shoulder is basically when the capsule of the shoulder joint adheses, and quite literally freezes!
When this happens, without treatment you can expect between 18 months and 27 months of moderate to severe pain in the shoulder.
By keeping your shoulder mobile, you can allow the shoulder to function as close to normal as possible. Most pain and inflammation in the shoulder reduces when the rotator cuff muscles can move most efficiently.
Try the pendulum exercise by hanging your shoulder down and swinging it in a pendulum clockwise and counter-clockwise for two minutes, three times per day.