Stabbing pain in chest

Hi. I've been having stabbing pains in my chest randomly, usually when I stand up, sit down or bend over. It feels like someone is stabbing me in the heart. If I take a deep breath it seems to go away, but then I have a mild ache for a little while. I haven't experienced this the last couple of days but my heart has been racing which has been giving me anxiety. I don't know if there was anxiety about the chest pain which lead to my heart racing or if the anxiety came from my heart racing. Basically I'm just wondering what the chances are that this is a serious problem or if it's harmless. I'd like to also add that I am a smoker but I only smoke 4-5 cigarettes a day.

[CCF HeartMD6]

Your atypical symptoms and relatively young age makes underlying coronary disease unlikely as the cause of your symptoms. Your symptoms may be related to disorders of the overlying skin, musculoskeletal system, or possibly GI system. However, anxiety may also be playing a role.  If you are noticing palpitations that occur on a frequent basis and are associated with symptoms, it would not be unreasonable to be evaluated by a physician who can perform a careful history and physical examination as well as some basic diagnostic tests.  However, your active tobacco use does put you at significant risk for developing serious problems with your heart and lungs in the future, and would heavily encourage you to quit.

[antisomnic]

I should add that I'm 23 and have been smoking less than a year.