My boyfriend and I had unprotected sex (withdrawal) last 13th and 14th which are my fertile days (last two days of fertile window). Today, the 22nd, I have noticed blood when I wiped, in the toilet and in my pantyliner. I also experienced mild cramps two days ago but it stopped. My period is supposed to start either the 26th or 27th (5 days from today). Is this spotting or implantation due to pregnancy?