Hi, I've been smoking on and off since I was 17,but it was probably a cigarette or two every 3 or 4 months. Now, I'm 19 and have started smoking again for 2 months straight, and have just noticed this pinching feeling located on my upper back where my lungs are. It started after I finished working out in the gym, and has been going on on and off. Is it something I should be concerned about, or am I just being paranoid?