Well I was riding my bike with my friends on a bike trail today.It was a really hot day. I was doing good but got a bit tired so we had to stop. After this when we were resting everything got really bright, too bright for me to look at. Then we started riding again and it stopped. Then after a longer time of riding we stopped for lunch, then it happened again. But this time it was so bad I got a headache. Also I got a really light headed and was sweating super crazy. I had to lay down in the grass and drink a lot of Gatorade (I didn't have water) For awhile, I thought I was going to throw up, but I didn't. Then eventually, it stopped. So then we went back and stopped a few times and it didn't happen. I don't know what was wrong. Does anyone know? Thanks in advance.