I had my cycle on december 10 I finished my pack of pills on december 15, but didn't get back on it because it made me really sick, but then had sex three days after that. I haven't had my cycle since december 10, but i feel crampy, tired, nauseous, i have a continuous headache, and lower back and pelvis hurt. this could all very well be my body getting used to my hormones again and my cycle about to start but ill be late tomorrow from my last cycle and I feel off.