So you may want to see if that is something you developed?
For me, I've had a lot of causes, both serious and not so serious ruled out. With all the tests I've had in the last year and a half, I've found out that my breathing problems are not caused by allergies, asthma, embolism, collapsed lung, hypothyroidism or heart issues (I'm going by my primary care doctor saying my heart sounds fine and no one expressing concern in the ER after my EKG results came in).
Loss of breath during exertion has always happened to me, even when I was at a healthy weight. I was just never the kind of person who could handle running a few laps around the gym. All my breathing problems developed out of nowhere last summer and they haven't gotten better or worse.
I just really wish I knew for sure what was going on - the fact that I don't know if what I have is serious or not adds to my anxiety even more. If it's only psychological, I will feel a lot better...but I don't know if I'll ever find out until after I get out of college and have my own insurance. I'm still on my mother's plan and she is often reluctant to take me to a doctor.
Thanks for the advice though. I'm happy to know that what I'm feeling doesn't necessarily guarantee heart issues (not saying it can't be, but I'm glad to know the anxiety door is still open).