I had terrible ongoing migraines for months. I was treated at Guys in London. since they ask me to take per day: 400 mg of b2 otherwise called riboflavin ( all at once) + 300 mg of Magnesium chelated ( 100x 3 times a day) and co-enzime Q10 300 mg (100 x 3 times a day) all of them after my meals. I have now been taking them for years without any migraines. I only get B2 on prescription the rest I buy in the internet as NHS doesn't want to prescribe, but golly! no migraines!
I also happen to have fibromyalgia so I exercise steady and moderately and have noticed that the above medication have proved to keep me fibromyalgia free too.
I hope this helps someone!