I am 47 and until 2 weeks ago was very healthy. Only July 6, I was doing my normal exercise bike routine when I started to feel some numbness in my left arm. I stopped riding the bike and went to work. About an hour later, it felt like all of the blood rushed out of my body. I was lightheaded, had numbness and tingling in all of my limbs, and tightness in my chest. I was taken by ambulance to the hospital and they did a bunch of tests including a stress test and found nothing. I then took a week off from exercising while on vacation. The morning after I returned, I went back to the exercise bike and the same thing happened, only the attach came on faster this time (was taken from the locker room to the hospital). More tests, including more blood tests, CT scans, and MRIs of my neck, head, arteries. The only thing they found was cervical spinal stenosis, but no one seems to think that is the explanation. Since I left the hospital the second time, I have had several more attacks even though I have not been exercising. Some even occur when I am asleep. They can last as long as 6 hours or more. I never feel completely better anymore (always at least slightly lightheaded and weak and numb in my limbs). Am desperate for any possible explanation since I can not really function in this condition. Any one have any ideas?