Discharge in placebo!

I’ve been on sprintec for two years. I usually have my period and it starts with cramps and back pain and medium to heavy flow. This past week I didn’t have any bleeding at all. Just browish discharge and awful back pain. Super emotional and tired all the time. I’ve never had this happen. I had unprotected sex two weeks ago (July 17) multiple times, we don’t use the pull out method... during the week of placebos, the first three days nothing happened, fourth and fifth was light brownish discharge and the sixth and seventh day was nothing again. What could this mean?