I started having migraines at 8 years of age, several a week. This persisted all through my life till 42 years later, I had a blood pressure emergency where I ended up in ER with 190/100 blood pressure. Thankfully, it never repeated and was never diagnosed but as a consequence I was put on Olmesartan, a blood pressure medication that relaxes the blood vessels. Eventually, the dose was reduced to the lowest, 5mg, once a day, to which I added 240mg magnesium glycinate, which they sell in Costco. I have been mostly migraine free since for several years and ones I do get are mild compared to before.
My cardiologist, who prescribed the blood pressure medication, is mystified saying that while beta blockers are a migraine prevention medication, olmesartan isn't a beta blocker and maybe it was just my (mild) hypertension which needed to be treated. I doubt that I had hypertension when I was 8 but I'm just thankful that decades of pain have come to an end.