I normally dont sleep with guys. But i had a one night fling, we used a condom and it was on june 23 and i cant remember for sure but im pretty sure my last period was june 18. Well on wed. july4 i spotted a little, i just thought on my period then it stopped, i spotted a little on friday night and again tonight sat night. its very light just little spots and is a brownish color it looks like old blood. Could i be pregnant? My lower back is sore but that could be from something else and my boobs are just a little sore. Normally i dont spot between periods which is why i am wondering. Can i be pregnant?i only had sex once and we used a condom.