29 weeks and keep passing out!

Avery
Three times in the past week and a half I've had an "episode" of nausea/ sweating followed by extreme dizziness to the point where if I don't lie down I pass out. The first time it happened I was driving and had to pull over and I DID actually pass out. 
Doctors don't seem to be making a big deal out of it. Basically, they're saying it's something some pregnant women deal with and that I have to take some extra care/ caution. This can't seriously be normal?!?!!!!