I have had to happen for as long as I can remember. I know when my vision get blurry and I feel like vomiting that it in most cases isn't going to end well. Happens most often when I'm sick but happened a fair bit when I was pregnant. I found myself making sure I have jelly beans in my bag and trying to get my bp back up - sometime a cup of coffee or glass of coke will be enough.
Def get your bp and sugars checked, these can change so much when pg.

Even when I was in hossy last week my bp was 105/65. But would then be backup again.

Gl xx