cramps and brown mucous in the last week of "active" birth controll pills?

Posted by campmom123

I am on birth control pills but had sex mid-month and about 5 days later started cramping and having brown mucous.  It's gone on for about a week now, and I have 3 more "active" pills.  I've had a lot of weird cramps and spotting on the pill before but never this late in the cycle or this type of discharge.  Could I be pregnant? Or do I have something wrong with me? (endometriosis?)