What would cause sudden loss of vision in both eyes?

[sadiekubat]

About 2 1/2- 3 years ago, I experienced sudden vision loss. I was making some dinner, I suddenly got very hot and went and sat down. My whole body was sweating, a lot. Next, my vision in both eyes slowly started closing in, all the way to not being able to see at all. A couple of minutes went by of complete blindness and then it slowly came back and I felt fine and that was that. Then, last summer, so maybe a year ago, I experienced it again. This time I was sitting with my boyfriend by a bonfire, I started to get really hot and remembered feeling like this the first time, so I got up and walked away, thinking maybe I just needed to step away from the fire. I went and sat in the front yard and sure enough both eyes lost vision again. It lasted a couple minutes againC but this time I threw up and after that it came back. When my vision comes back I feel perfectly fine. I haven't seen a doctor yet, but am making an apt tomorrow. I suffer from frequent migraines, just haven't had the two link up at any time. Any suggestions of what may be happening? TYIA