Unprotected Sex, No Ejaculation, Have Continuous Brown Sticky Discharge Since. What Could This Be?

I had my period last the starting date was 15th of Nov and ending date was 19th of November and on the 28th I had unprotected sex but he pulled out before he cam I am 20 years old with two children already and on the 2 of Dec I started getting a brown sticky like discharge coming out of my vagina and I still am today and this has never happened before and my youngest is 20 months what could this be