My boyfriend and I had unprotected sex two days ago. He pulled out, but I do realize that there are sperm in precum. I started getting light brown discharge yesterday (the day after we had sex). My period is due in 4 days, and I have a roughly 33 day cycle, and I chart everything. Also, yesterday, I was aching all over. I feel better today, but the brown discharge is still there. Could I be pregnant?