I went to the doctor the other day for a Physical, and told my doctor about the chest pain, shortness of breath, and fatigue I have been experiencing lately. I'm under 20, so this wasn't heart related. He had me do a breath/lung strenght test, which showed that my lungs are storng, so that isn't the problem. Then he had me do a lab test, then an Oxygen level test, where I speed-walked around in a large circle for 5 laps. My oxygen level went down to 80- that's not good. More than likely, he said, I'm losing blood in some way. I could be anemic, have a bleeding stomach ulcer, or something else. I don't know. I'm waiting for the test results... and am feeling pretty down. Good to get that off my chest!