Sharp pains in left side of chest.

Hello all,
I'm 20 years old and for the last few years I have noticed a reoccurring sharp pain in the left side of my chest.  The pain lasts only a few seconds at a time and sometimes goes away right after - but sometimes, like today for instance, its been with me for over 12 hours.  It is a very uncomfortable feeling even when the sharp pains are not there because any quick movements or change of position can trigger them.  
I have been monitoring my BP and heart rate all day and I'm pretty sure it is not PVC or PAC, because the heart rate is constant even during the pinnacle of the pain and the BP is the average of 125/75, pulse around 60.  I want to rule out gastrointestinal possibilities too, because the pain is on the left and nowhere near the esophagus.  I did have asthma as a kid (grew out of it) but if it was pulmonary I'd think for the pain not to be focused on just one side.  
I feel like I'm a too young for any ___carditis problems since I do take care of myself pretty well and am not overweight.  Any thoughts on what this could be, advice, or anything of that nature is much appreciated!
Thanks,
Manny