Add not being able to breath to that and I have the exact same problem. Told my doc and she says its part of pregnancy. But feeling like I am going to pass out I dont think thats normal.
It could be orthostatic hypotension, where your blood pressure drops quickly when you stand up. It's very common in pregnancy and is not usually harmful, just sit back down if you feel like you're going to fall and take your time getting up from sitting or laying down.
U r prolly anemic..do u take iron suppliments?
Are you getting hot?
Maybe even if you're not feeling hot you should lay down in some cool air.