Sometimes a muscle pinches a nerve in your shoulder and that nerve gets really angry. Hot, fiery, numbness and tingling pains shoot down your arm. You feel it in your forearm wrist and hand.
Try pinching your shoulder muscle with your opposite hand and relaxing your arm. Repeat for several minutes. If this is the cause you should feel some relief. Alternate hot and cold compresses to encourage circulation. the ice should help calm the nerves.
Stretch your shoulder and chest muscles using a wall and a doorway, like this
and like this
Work the kink out by following the shoulder mapping components of force exercises. http://www.exrx.net/Kinesiology/AnglePull.html#anchor1499250
Just move gently and lightly. Like your giving yourself an internal joint massage. If you feel ANY pain instead of relief, stop immediately and have it checked. You may have torn a ligament.