Hi,
I'm so sorry you're having all those headaches! I know exactly how you feel. I've always been prone to headaches, including occasional migraines, since I was a teenager. When I first got pregnant, I dreaded going 9 months without any drugs for them, but thankfully I didn't have nearly as many headaches that whole pregnancy and tylenol worked for those I had (it never worked when I wasn't pregnant). Second pregnancy...same thing.
But this pregnancy was a different story. Daily headaches made me miserable the first couple of months and tylenol didn't touch them. Then I read somewhere that magnesium supplements could help so I tried a sample of a product my husband brought home from his chiropractor...instant relief!! My headache disappeared overnight and I have not had one headache since I started taking it ~6 months ago, except for one day when I skipped the mag. the night before, thinking "I probably don't have to take it EVERY day..."
Anyway, the stuff I take is called Natural Calm, and I take about 1 tsp. per night before bed. It has been absolutely wonderful for me; it also helped me sleep alot better, but I would keep taking it just for the headache prevention benefit alone.
Good luck, mama! It sucks to have to deal with headaches when you're pregnant.