Help me please. Im really confused.

Hey! So about week before my period I had brown discharge for 4 days and I found there piece of something. It has never ever happened to me before. Than this month I didn't get my period. I have regular cycle but now I'm late by 8 days. Also my nipples are hurting a bit. I don't know what is happening. I don't think that I'm pregnant because I had sex only twice since my last period and our condoms were okay. Do you know what it can be?