TMI!!! Need opinions

I had protected sex with my boyfriend on August 5th. We checked the condom it hadn't broken or leaked. I'm supposed to get my period on the 23rd but starting the 15th I started spotting. It's gotten a little heavier as the days go by and its lasted for 4 days (all through out the day without stopping.) Any idea what's going on? Is this normal because I'm freaking out