For the past year, everytime I have my period I have a bad headache which can last up to five days
According to The National Headache Foundation :
"Menstrual migraines are primarily caused by estrogen, the female sex hormone that specifically regulates the menstrual cycle fluctuations throughout the cycle. When the levels of estrogen and progesterone change, women will be more vulnerable to headaches. Because oral contraceptives influence estrogen levels, women on birth control pills may experience more menstrual migraines.
The menstrual migraine's symptoms are similar to migraine without aura. It begins as a one-sided, throbbing headache accompanied by nausea, vomiting, or sensitivity to bright lights and sounds. An aura may precede the menstrual migraine."
The level of estrogen is also mention in an article by Dr. Judith Reichman, in a Today Show question and answer about "when your period brings a major headache ."
Both article discuss treatment of various forms and you may want to read them or discuss the options with your doctor in ameliorating the severity of your headaches.
Thank you very much