Bloody discharge

So I’m 22 years old. My periods are always regular. My bf and I last had sex in August and then I got my period...because he is gone abroad for a month. My next period is not due for another week and today, after I wiped, I noticed some blood in the discharge that was on the toilet paper. I’m so worried because this has never happened to me before. Does anyone know why this happened to me? Has it happened to you before?