People greatly under estimate the power of caffeine. You can absolutely have withdrawls from it. Also depending on where you live it could have been allergy related. I am in Texas and the weather has been throwing some serious challenges at us. One day it is spring time pollen. The next day it is high mold spore counts from rain. Do you suffer with migraines or tension headaches normally? Did you recently abruptly stop caffeine? All things to consider. Many times with migraines there is sensativity to light, sound and nausea. Happy that you did get relief finally. Just FYI women seem to suffer more from migraines while men suffer more from cluster headaches.