Small sometimes sharp pains in the left part of my chest under my breast

karynda,

Thanks for your question. 

It's difficult to say with any certainty what the cause of your pain is.  It could be muscular, or a problem with your rib cage.  Though not typical, there is still a possibility this may represent heart disease.  Your smoking may or may not be a factor in this pain.

The safest thing to do is make an appointment to see your doctor in the next couple of days for an evaluation.  He/she will take a history, examine you and perform an electrocardiogram.  Then your physician will be a better position to determine what the cause might be.  He may request further testing before coming to any conclusion.

Best wishes and feel better.

Martin Cane, M.D.