Low blood pressure

I am 37 weeks, and this is the 3rd day in a row that I have nearly fainted due to low blood pressure. I call my OB’s on call number every time and the same nurse has called back 3 days in a row, telling me that there is nothing she can do and that I am obviously dehydrated. I asked if I could come in and see the doctor and she said he is booked to the max and has no space. I asked if I should go to L&D; and she said it’s not necessary for blow blood pressure... I don’t know what to do if it happens again! I am not dehydrated, I drink more than enough water every single day, and she wouldn’t even squeeze me in to see the doctor! I am more than pissed. I nearly passed out today and it has me worried!