I Have Persistent, Constant Mild Pain In Right Shoulder Blade

I have persistent, constant mild pain in right shoulder blade area for 2 weeks. raising my right arm above head makes pain go away. Sitting upright in chair is uncomfortable. I'm 52 years old, I smoke, for 4 years now. I know, who picks up smoking at 48. Any over the counter medication suggestions or vitamins would be appreciated. Thank You.