Pain near heart area?? help pls!?

I am experiencing a dull pain at the ribcage edge area, on the left side of the upper abdomen. There would also be pain on the left side, just near the heart, few inches down the armpit area. My heart beats about the same way as usual, but sometimes( like once or twice) does it become more intensive for a few seconds.

It is intermittent and just dull, not sharp. Doesnt hurt when i breath in deeply. Have not tried excercising, so i do not know if it does help. The pain is coming back more frequently these few days and have started about a week ago.

I thought of it as nothing serious but would seriously consider seeing a doctor if it continues these few days. Just wanna know any possible causes of it. I have been reading up a few articles and forums but seem to get nothing out of them. Pls help! Thanks a lot.