Anyone else gone through this?

Can implantation bleeding last 4 days? I started spotting light pink blood around 4 days before my period, but it turned brownish yesterday and still brownish today, no clots, period is supposed to start tomorrow, out of my 4 pregnancies I have never had implantation bleeding, I did has a miscarriage in early July also. I’m just confused, I will be buying a test later today too, but just curious if anyone’s had 4 days of implantation spotting/bleeding.