If you've always gotten them, I wouldn't worry about it being blood pressure or anything like that. My sister gets them, and gets a lot during her first trimester. (They go away after that! Hurray!) She has some prescription stuff that she can take, but before that, she always tries a hot shower, an ice pack on her head, and peppermint essential oil on the temples, behind the ears, and one other spot.... can't remember. Anyways, it's supposed to be a good natural remedy for migraines, and if the head ache isn't too bad yet, sometimes that does the trick.
Hope yours is relieved soon! All the best.