Pain then "popping" in chest..
 

Hey there healthboards.com;
I seem to be having a problem and im wondering if anyone can help me out...
Since last Thursday (5 days ago) I have been getting these random chest pains. Ive gotten them maybe 2 or 3 times a day, it comes from inside the chest, about 1 inch left from the center of my chest, and just above my "nipple line". I stress that its internal and not external.

I'm getting a sharp pain from inside like a tightening sensation, so i usually push my shoulders back to stretch when i get this feeling, i then usually feel (and hear) a pop, and the tightness immediately subsides and vanishes.. th whole ordeal lasting maybe 2 seconds or so.
I am really worried that it may be serious like the heart or something.. I just had the experience now at 6am and it has forced me to get up and come on here, i cant fall back asleep....

I am a 17 year old male, Lead an active lifestyle, I eat sensibly, Attend the gym three times a week, I have a Body Mass Index of 21.7 (very average and normal weight), and I have no and never had any medical conditions.

The only thing i have done out of the normal in the past 3 weeks is stop attending the gym, as I have alot of A-level exams with school at the moment (UK Student) Which has been stressful and time consuming, so i have not been to the gym for about 2 or 3 weeks.

I am currently home alone as my parents are on holiday, they are back today. - random info just as an FYI.

Please help me if you can. Kind regards.