Sandra, that's what I found from the (few) migraines I used to have. If I got the ibuprofen in soon enough I was ok (still had the migraine, but it wasn't bad). But a few times I woke up with one already started which is just not fair And once it was really going it didn't matter how many pills I took, they did jack squat.
She eats almost the same thing for breakfast every day - eggs and onions cooked in olive oil and either dark chocolate or cocoa nibs plus some kind of fruit ( that changes). I do know that chocolate (especially dark) is a trigger for many so that could be a possibility in combination with PMS maybe? But it's her first migraine so we don't have a history to go with yet.
I don't want her to keep a food journal though because she's at that age where food issues can crop up. She's very strict about the paleo (other than the chocolate) and while she eats lots of good fats and plenty of calories and healthy carbs (ie - produce), she refuses to eat non paleo ever, even with friends so I just want to keep an eye on it and make sure she doesn't tip over from healthy to food disorder, you know? But I will try and keep one for her, which is easy enough because all her meals are homemade.
For now I'm going to keep a food log myself, remember to give her the magnesium/calcium supplement every day and just see what happens. I only had a handful ever so hopefully she takes after me and not her grandmother who suffered from them for decades.