Dizziness and headaches anyone?

I'm 17 weeks and bout 2 days. For about two weeks now I've been dizzy off and on no matter what I do sitting standing laying down dosent matter. My vision goes dark or really blurry and it's like the worst drink feeling in the world followed by a headache. I brought this up to my doctor and he was like your pregnant its normal and that was it. (Another reason I'm switching doctors) im debating on going to the er tonight it it dosent let up some. I'm just wondering what you ladies think this could be? Fist time in two pregnancies I've ever had this happen so I'm a little scared.