Confused

So, I've been on the implant for a while, and I had my last period end of March this year, and I've been having unprotected sex since October 2015, today (3 months after my last period)  I noticed a tiny bit of blood in my knickers, then went "exploring" and noticed more blood higher into my vagina, I had bad pains earlier today, is this a period? Or is it pregnant bleeding?