Can a menstrual last only 2 to 3 minutes or is it Implantation.?

ok i went to the doc for a preg test on Jan 5thwhich was negative.a few minutes befor i took the test i went to use the bathroom to give urine and noticed dark watery blood it only was only when i wiped.after that nothing took a blood test the same day hcg level was 1 did i test too early could the bleedin have been implantation my period is due tomorrow Jan 8th i believe i ovulated Dec 27..no bleeding bessides the one time at the doc but i have wierd cramps off and on now...not like af i dont usually cramp befor af or when i start i usually cramp 4days into af.