Bleeding 3 days after sex

I went to the bathroom and noticed spotting on my undies. When wiping a light brown/red blood was visible... We conceived a day before ovulation (3 days ago) I googled implantation 3 days after sex and some people have fallen pregnant afterwards. Has anyone had this? My period isn't due for another week. Please no negative comments we are TTC and trying to stay positive. We plan to head down to the doctor tomorrow just to make sure all is okay.