What Causes Abdominal Cramping And Brown Vaginal Discharge While UPT Is Negative?

I stopped taking my pill about 7 weeks ago because I missed two and intercourse then missed two again. I stopped taking my pill. And had a withdrawal bled about 6days after. Then about ten days after u had another heavy blead. Now when I thought my period was due, Tuesday I started to have brown dischargeand it continued for five days. I have had light abdominal cramps like period pains and crying for no reason??? After three weeks I did a pregnancy test and it was negative but could I still be pregnant?