6 days late... then had light bleeding for 2 days

I had been off birth control 3 months ago and just before that was on IUD for almost 3 years. Ttc baby #2 and after a month in of being off the birth control, then my period started since I havent had one when I was on IUD mirena. And since then had a period on time each month. But this month I was 6 days late as of last week and then after the 6 days of still being late, my SO and i had sex and then afterwards noticed I was bleeding a little of brown to light pinkish on him and then had the light to medium bleeding for 2 days and it stopped and havent had any bleeding afterwards. I had put a pad on and it didnt fill the pad up or anything. Could it be a late period/short period or a late implantation and can late implantation happen?