I am 41 and have some intermittent sharp shooting pains in left breast area, left shoulder . Had ECG yesterday and all ok, ribs sore to touch as are shoulder/neck muscles. Had very sharp pain today to want to emergency, heart trace 2 hours fine, heart X-ray fine, no enzymes in bloods. Told likely muscular skeletal. The area buns at times and feels full. Does it sound muscular to you?