By Stephanie Prendergast, Cofounder, PHRC Los Angeles   Severe menstrual pain is not normal. If you experience severe pain during your period it is possible you are suffering from an underdiagnosed disease called Endometriosis.   Endometrial tissue lines the uterus. In response to hormonal influences, the endometrium of a healthy uterus thickens and then sheds through the cervix, through …