brown cervical mucus and then sharp left pain and horrible c

Hi! Last July I had a baby via C section and opted to get a tubal ligation. This month, approx. 2 weeks before my period, I had a release of brown cervical mucus. then came about a week later ,Back ache and horrible sharp pain along with tenderness on my left side pelvic area. then I had horrible cramps during the days that I was late for my period (about 3 days late which I am never late for ). What could all this mean?