I had sex with my husband two days after my period and two days ago. He used the pull-out method. Today, I am starting to feel lower back pains just like I do when I start my period. The thing is, the "period" I had before that has very dark blood and barely any cramping, making me wonder if my uterus was just cleaning out old blood and lining to shed a new one. I doubt pregnancy symptoms happen THIS early, anyways. But, what could be making it do this? Anything else other than pregnancy or period?