Implantation?

Just some advice please ladies! AF isn't due until Friday and she's usually pretty dead on day 31 give or take literally a day either side. Today (day 27) I've had really mild cramping on one side and some really faint pink spotting. I only saw it for a couple of hours this morning and now it's stopped, and was only there when i wiped. Has anyone else had this around this time? I had sex 10 days ago during my fertile window. xx