What Causes Stomach Cramps And Nausea Before A Menstrual Period?

I ve been taking Seasonique for over 2 months now. In about 2 weeks, I m suppose to get my period. If the last couple days, I ve been feeling nausea, warm, and have had on and off crampy-like pain in my stomach, pelvis area, and favored on the right. I feel hungry, but when I eat, I feel nausea. I have not thrown up, and I ve never missed a pill. What could be wrong? Am I getting period cramps early? Is it a touch of stomach flu? Is my body not reacting well with my pills? Or is this more serious that I require medical attention?