★★★★★
Here is a very quick and cheap thing to try, because all it'll cost is a small bottle of the niacin form (nicotinic acid) of Vitamin B3! I note that B3 is not listed under the Vitamins on this site, and B3 is not in the Remedies list under Migraines, either.
From the Linus Pauling site (well, one of them):
Http://www.orthomolecular.org
Two Case Reports on the Treatment of Acute Migraine with Niacin: Its Hypothetical Mechanism of Action Upon Calcitonin-Gene Related Peptide and Platelets
Jonathan E. Prousky, N. D. , FRSH; Erika Sykes, N. D. (Cand)
http://www.orthomolecular.org/library/jom/2003/pdf/2003-v18n02-p108.pdf
At the first sign of aura, he orally ingested 300 to 500mg of niacin, slightly chewing the niacin pills to allow them to dissolve slowly in his mouth. Hall found that the benefits of niacin were most pronounced when taken on an empty stomach, although it was noted that there was still a MH relieving effect when taken after meals. Additionally, he remarked that the migraines were resolved when intense flushing occurred.