What Could Cause Delay In Periods?

I am 5 days late for my period took a test two days ago it was negative past night I had a small amount of pink/red blood which was followed by an hour or so of brown blood only when I wiped. This morning there was nothing then this afternoon I had cramping and when I go to the bathroom there s clots when I wipe but not a lot of blood and they are dark coloured.. So confused please help