I have had migraines on and off for a while, but lately I have been having spotty vision and it looks like I have been looking at a light to long. Then after that I get a headache on the left side of my head. Then after 10 or 15 minutes it all goes away. Now that I'm pregnant it happens about once or twice a week. What could it be?

We can't diagnose on the internet, but this sounds serious enough to make a doctor visit instead of asking strangers what it is. Especially since you are pregnant. Get a proper diagnosis from a professional.