A headache just hurts, a migraine can make you sensitive to light/sound/smell, have nausea, vertigo, neck and eye pain, the list goes on. Plus migraines can last a few days while a headache can last a few hours. My mom and grandmother suffer from migraines and I have had a couple, there is a difference. Speak with your doctor.
Magickally, I think you're draining your body of energy and not using the energy around you. Study and do some energy work [charge, ground, center] before casting more spells. You might also have a blocked chakra, try balancing them from the root to crown.