brownish discharge!?!

So I had like brown kinda think discharge for like a little bit today. With like a little bit of blood. My period isn't due till next Monday(10/9) I had sex but with a condom this passed Saturday and then back in August when my period was already 4 days late I got it 3 days later so my period was a weeks late but I hadn't done it in months before then. No pain or itchiness or any pregnancy symptoms any ideas??? I'm 16 if that makes a difference