What Causes Severe Stomach Cramps After Taking Pregnot?

Hi doctor I took pregnot tablet I bleeded after taking the 2nd tablet . but the bleed was v little not even for a day and it stopped . now the last tablet is left to b completed. I n worried whether the tablet is working or not. I had severe stomach ache cramps n all but no bleeding. I think I was 2 weeks pregnant as my this month period got delayed by 5 days. . please help.