Extreme dizziness ?

This is my second episode and I’m extremely concerned on what it could be. I havent eaten yet so it could be that (it’s been 3-4 hours since I’ve woken up) I went to Walmart to grab a few things and I get this overwhelming dizzy spell accompanied by sweating and being cold at the same time, extreme nausea and just a feeling that I’ll collapse if I don’t sit somewhere immediately. I’ve gone out before without eating and I’ve been fine. Like I said this is the second time this happened to me and the first I was in a grocery store and had to sit on the floor. I also found myself breathing rapidly. It goes after a few minutes and then I’ll be fine to keep moving then return 10 minutes or so later. I just want to know if this happened to anyone else. Also I’m 26 weeks if that changes anything.