Brown discharge: early AF or IB??

So I’m 12 DPO and have had negative pregnancy tests up until today. My period is due in three days. But for the past three days I have had cervical mucus with brown strings in it. Only when I wipe not enough to fill a pad or a panty liner. It’s really goopy and now it’s kind of going away. I’m also crampy and super bloated and my lower back is killing me. I’m not sure if this is a period or just maybe implantation bleeding? I haven’t had implantation bleeding with my first two so I’m new to this.