I do have the congenital disease, pectus excavatum, which is rare for girls,
and does cause me shortness of breath
and quick fatigue with any sort of physical activity ( even walking up the stairs). Im high school I was an avid soccer player, and cross country runner, until I started passing out. Which is when I was diagnosed. I also get horrible nose bleeds about 3 times a week, my doctor suggested I try sleeping sitting up, which is really difficult haha.