Dizzy all the time

Zoe

I’m struggling guys, I’m 26 weeks pregnant with my third and I’m terribly dizzy like walk right fast get a dizzy feeling, turn my head dizzy anything that’s not sitting in one place only and not moving my head is the only time and even then I get random spells. I don’t know what to do i drink more than a half gallon of water a day and take vitamins and nothing helps!!! Any idea what’s going on or anyone dealing with similar symptoms!?