What Causes Vaginal Discharge And Lower Abdominal Pain?

I am 30 yrs. old, 5'4", and have 3 children. Although mu uterus is tilted backwards, I have been experiencing slight pain in my lower abdomen. Similar to slight menstrual cramps. At the same time there is a gush of discharge that started off light brown but, now light pink. I'm not due for my menstrual cycle for 2 weeks. I have not had any new sexual partners and my pap smear was fine. Can u tell me what could be wrong?