What Causes Neck, Collar Bone And Chest Pain?

5 days or so of sharp centralized pain that throbs with pulse at left side of neck, collar bone and chest at edge og armpit. hurts and throbs most while at rest sitting/reclining; goes away with activity. pain also feels better when leaned forward. no swelling or lumps or redness. when I press on sore area it hurts more. so far my research has ruled out heart issues and doesn't feel like a pinched nerve. any ideas?