Consistent fainting/dizziness. 30 weeks

Anyone else having persistent fainting spells or dizziness ? I got a prenatal massage two weeks ago, and passed out on the massage table, and now today at work i nearly fainted again !

I tell my doc, and they insist I'm dehydrated, or aren't eating enough- i drink enough water to where my pee is CLEAR & i eat and snack ALL DAY.

- i don't have anemia

- i am not hypoglycemic

- no other underlying health issues

- healthy pregnancy.

Any clues as to why i might be experiencing this?!