Make sure you're drinking tons of water. And take a tylenol with a coke that always helps me. I used to get really bad headaches during this pregnancy now I stay super hydrated and that's helped a ton.
If your doc checked your blood pressure, and it's not a completely severe headache, it's a totally normal pregnancy symptom. It can be caused from stress, the extra weight we're carrying around, posture changes, lack of caffeine, diet, etc. Here is a post from a week or so ago when someone asked about migraines, and there are lots of ladies' suggestions on how they deal with it.
Re: Headaches
Maybe chiropractor & massage will help.