Tmi photo

So my hubby and I had unprotected sex one day before my period started. My period is normally always the same in flow and length this cycle was very strange it was start stop ect ect. The past two days which are supposed to be the last days of my fertile window I have been having this/ light pink discharge. Could this be late implantation bleeding ! I know sperm can live inside for up to 5 days I believe. I'm 4 months pp on the 5th. Spotting/ discharge like this is not normal for me even after birth.