Hello,For the past several years I've had a reaction to high-energy workouts or in general things that get my heart rate going.I'll be going strong, then slowly I'll begin to experience cold sweat, clammy skin, tingling in my extremities, pressure in my ears accompanied by slight ringing and dulled sense of hearing, heightened sensitivity to light, and eventually - as I found out yesterday - loss of consciousness. Everything is normal at my physicals and I've had an ultrasound of my heart and been told everything is normal - any idea what might cause this? (25 years old, 5'9.5", 168lbs)-Peter