Hi, I am 16 years old, am very involved in sports, and have very good conditioning compared to many other athletes my age. I have been experiencing random spells where I suddenly become short of breath, my heart rate becomes very rapid, I have muscle spasms throughout my body, and become dizzy/ lighthead for several moments, feeling very poorly afterwards. They are random, sudden, and almost always occur when I am non-active (sitting, lying down, etc.) I have never experienced them while being active. I have no other medical problems and have no idea why these 'spells' are occurring. Please help and thank you.