PLEASE HELP

Rebecca
So I am on day 97 of this cycle. I normally have around a 50 day cycle. My boyfriend and I had unprotected sex once, but he pulled out, and that was about a month and a half ago. I took one pregnancy test a couple weeks ago and it was negative. Around that same time, I experienced a little bit of brown discharge for about a day or two. Implantation bleeding? I haven't had any pregnancy symptoms but I don't understand how I'm this late. Has this happened to anyone?!