pain shooting down arm....my dear you need a Massage Therapist.....you probably do have a pinched nerve (from muscle or bone)...there are a few muscles that if released (via trigger point work) may alleviate you pain..
..You sound like the classic case of TOS (thoracic outlet syndrom). Compresion of neruvascular bundle (brachial plexus) either from a) scalene muscles b) pectoral muscles c)compression betwwwn the clavicle and first rib.....
It could also ne neuralgia or ulnar nerve (funnybone) compression at the elbow....