help! day 14 of cycle and bleeding

Jacey

my periods are always normal. yesterday was day 14 and I had intercouse and noticed and light color when I wipped. then I started spotting super light then rest ot the day. Today is day 15 and Im bleeding brownish blood not heavy but its not normal for me. what could this be? my cycle is 28 days so I should be starting for almost 2 weeks.