I'm an 18 y.o female and I know it sounds dumb, not like a medical condition, but I get a tight pain in my chest when I walk uphill, run for more than 5 seconds outdoors (on a treadmill I don't seem to get it as bad), or swim for more than 5 seconds. I also experience shortness of breath, and I end up a little nauseous, but I attribute that as a result from whatever makes my chest hurt. It feels like my lungs aren't getting enough oxygen, but even if I take a lot of even, deep breathes, I can't walk up moderate inclines for more than 10-15 feet.
I was given an AutoMax inhaler a few years ago, after my GP made the diagnosis of "exercise induces asthma" without having me tested for anything. The stupid inhaler just made me shaky and have a cough the next day. I don't get the feeling that I can't get enough AIR in my lungs, just that the oxygen isn't in my blood. I don't have trouble breathing, I don't ever wheeze or cough much. This is why I'm starting to think it's my heart, not my lungs.
I've noticed that it's the worse when I have extra weight on myself (a backpack, etc.) which leads me to further believe it's my heart. I also had a mild heart murmur when I was a kid, but it was gone by the time I was about 10. I also have a personal history of high cholesterol (over 210 for a few years when I was 11-12) and probably still do.
I want to have some sort of physical exertion test or something (like they use to test for asthma) but I don't know who to see, or what type of test would figure out heart or lungs...or something completely different, who knows.