Hope you're feeling better. I too have found caffeine is helping a little. I was getting headaches daily with a few migraines here and there, I am now 24 weeks and the last 2 weeks, the headaches seem to be almost gone... so hopefully it passes for you too.
My doc said the same thing as one of the pp, that as soon as I feel the headache starting, take tylenol, some caffeine, and try and stop it from progressing. I also have found having some gatoraide has really helped, I have been making sure that I am super hydrated, but I wonder with the heat if water just isn't enough. I also check my bp regularily but it's been fine.