What are some common causes for random sensitivity to smells?

Perhaps migraine: Not unique for migraine patient to get rather ill with scent of certain perfumes, or other aromas. Some pts get allergies and ambient chemicals can even cause an asthmatic attack. Some medications may distort tastes and smells and cause adverse rxtns. Some complex partial seizure patients experience foul odors prior to sz, and may be provoked by certain odors rarely.