I get the same type of migraines. I went to a Dr and he gave me an ALCAT.  It is one blood test the checks for allergies and sensitivities to hundreds of items--mostly food.  My doc had me go on a diet for 6 months woithout any of these foods, and my migraines stopped.  If I eat some of the items on the list (e.g bananas, or carrots), I will get a migraine most of the time within 3 days (Sometimes I don't get a headache).  I don't know why, but it doesn't always happen right away.  Even some of my airborn allergies disappeared and I rarely need to use my inhaler now.  I don't understand the connection (if any), but it helped me.  It can't hurt to check it out.