For the 3rd time in 2 weeks, I have started to pass out when exercising. It is a decent intensity, but by no means a crazy hard workout. My chest hurts, I am short of breath, and start to see spots. I feel awful. Besides when I m working out, I am exhausted. I do have asthma, but have not been wheezing, my sats are 99, and peak flows are good. I just started taking claritin-D instead of regular claritin, and am wondering if this is the culprit, or if I need to get my heart checked. I am a 32 y/o female, never smoked, don t drink, 140lbs.