Off late any time i have a severe migraine i get nausea n swollen scalp what can i do to eliminate the swelling.and why does it swell at all ?

Migraine: is a serious and complex neurologic disorder. Unilateral throbbing headache, dizziness, weakness, visual disturbances, blurry vision, nausea, sensitivity to light or sound, paresthesias and even partial blackout may be present during the episodes. The IHS offers specific diagnostic criteria for migraine headaches. See an orofacial pain or headache specialist.