Ok im a little concerned im a 22 yr old female experiencing a dull aching pain in upper back feels like the lung. Feels like pressure like something is just resting there slight pains in between shoulder blade. Progressively gets worse throughout the day. Its there laying down sitting up standing up really is becoming an aggravation. I do smoke almost a pack a day. But this is not a strain feeling , nor being sore. Just feel as if im carrying weight on my left side.