What are common causes of shoulder blade pain? no trouble breathing and normal pulse. only hurts w/ certain movement of torso/arm or in "bad" position

Musculoskeletal: Mid-twenties male with shoulder pain aroused by certain positions suggests muscle/tendon sprain; perhaps related to labor or sports activity. There are several muscles involved in the shoulder mechanism. A doctor or physical therapist who understands shoulder anatomy and function can discern. Rest and avoidance of offending activity usually ameliorates.