Dizzy Spells

Hi I’m 30+2 weeks pregnant. Lately I’ve been having several episodes of dizziness. Just had an appointment Thursday and talked to my doctor about it and she didn’t seem concerned at all and said maybe it’s sinuses and suggested over the counter medication . It’s getting worse to me to the point when it happens I have to lay down and close my eyes for awhile I sometimes have to take a nap to feel better. Just yesterday I had to pull over to the side of the road and let my husband finish our road trip because it happened while I was driving. I am anemic and take my iron medication faithfully every night so I would think that she would want to draw my blood and see if my medication is helping or not. I stay hydrated throughout the day so I know that’s not the problem. I have no idea what it could be is any one else having this problem?