I am 20 weeks and I was walking around the block with my sister, because my Dr told me I needed to stay active. I had stopped to talk to a neighbor and I got dizzy and lost my vision. My stomach also got very hard when I was walking. I was fine once I sat down but I was not over heated or over doing it. I'm going to the er of I feel bad again and calling my Dr tomorrow regardless. But anyone have any ideas of what it was?