Pregnant?

So I had sex on the first day of my fertile window and I took my way the next Day which was Tuesday. I got sick and then on Sunday(Feb. 4) I started to bleed but my period isn’t due til Feb. 15. So why did I bleed? I know spotting is a thing for plantation if you are pregnant but that usually doesn’t happen until 6 days after you fertile window while I started to bleed on my last day. The blood was red but then sometimes it was pink/ brown. I would say I have “cramps” but they aren’t bad at all.

Thank you!