Overheating and feeling terrible

So I’m freshly 28 weeks pregnant and not feeling my best! The past few weeks I haven’t felt that great. Almost every day I get hot to the point of feeling like I’m about to pass out, a few times I actually have. I thought maybe it was low blood sugar or something but now I’m noticing it happens even when I eat. It happened a while ago at one of my sonogram appointments and the doctor had said it could be some kind of syndrome (I can’t remember the name for the life of me). But I was wondering if this happens to any of you?