Common association. The area in the brain stem that triggeres migraine headaches is physically next to the vomiting center. The two areas interact through a neurotransmitter Dopamine. There is a combination of medication such as Reglan (metoclopramide) and ibuprofen may help your headache and prevent the stomach ach is taken as soon as you experience headache.
Migraine. Migraines typically cause nausea. It affects more than your head. If you have not seen your doctor then do so. Phenergan (promethazine) and tryptans can help abort the migraine. I highly recommend acupuncture and chinese medicine to get to the root of your imbalance and to prevent further headaches.