brown discharge after sex and i havent had my period yet this month..very worried idk wats goin on

hi im 22 and me and my bf have been havin unprotected sex for a month or so...but this time we had sex and right after i noticed brown discharge after we had sex and when  i peed right after chunks of the discharge came out cld i be pregnant or othe problems..ps i have a son now but i nvr had this happen when pregnant with him???