possible headaches as a sign of pre eclampsia?...

For a little over two weeks now, I have been getting headaches every single day. I used to never get headaches at all but all of a sudden now it's a daily thing. It starts off with the back of my head and moves to the sides then to my eyes. I've also been seeing black spots in my vision. It's mostly at work but recently it's been everyday. I told my DR and she said it's a lack of water and oxygen to my brain. I've been drinking about a gallon of water a day and have been sleeping 8-10 hours a night. Tylenol, naps, snacks, ice water, none of that is really helping. Should I be concerned and ask for a second opinion?