Implantation bleeding or old blood? 7 days before period

Sorry for the TMI

Quick info

- regular cycle ..3-4 days here and there sometime

- has unprotected sex 2 days before ovulation on 11th aug and he came inside me to certain extent and then pulled out ( during ovulation we used pull out method )

- had my ovulation during 13 to 17 aug

- my next period is due in 5 days

- having mild cramps in abdominal area and feel like I’ll start now anytime

- had pink water gush 3 days ago and since then having brown discharge when wipe.

What can it be ? I’m not in any birth control but I was diagnosed pcod since when I was 23-24 years

But thank god im having regular cycles