Your head hurst because of Prostaglandins,
Prostaglandins are chemicals a woman's body produces that cause many of the symptoms associated with menstrual discomfort. The tissue that lines the uterus makes these chemicals. Prostaglandins stimulate the uterine muscles to contract. Women who have high levels of prostaglandin experience more intense contractions of their uterus and more pain. Prostaglandins may also be responsible for vomiting, diarrhea, and headaches that accompany painful periods.
Hope I helped...Ü
Prostaglandins are chemicals a woman's body produces that cause many of the symptoms associated with menstrual discomfort. The tissue that lines the uterus makes these chemicals. Prostaglandins stimulate the uterine muscles to contract. Women who have high levels of prostaglandin experience more intense contractions of their uterus and more pain. Prostaglandins may also be responsible for vomiting, diarrhea, and headaches that accompany painful periods.
Hope I helped...Ü