implantation or just mid cycle bleed?

M
Help! I am on cycle day 20 of a 28 day cycle and 5dpo. I had light spotting this morning but it was more red than I would imagine implantation spotting to be? I am a first timer and have never experienced any bleeding mid cycle! It carried on for about 5 or 6 hours and is mostly gone now. It was also very light (not enough to need a pad for) and no af symptoms. I have very regular periods so not thinking it's af early? Could this be implantation? Or is my cycle just messed up this month?