What Causes Bleeding And Pain After Periods Stopped?

Hi Doctor, I had I pill on the 7th or 8th day after my periods & now on 12th day after my periods started I am again having slight bleeding & abdominal pain. Is it because of I pill ? I have taken I pill 2-3 times before in my 5 yrs of married life but never faced such bledding or pain. I am really really afaird if I have got some severe side effects of that pill. Please help me as I am worried about my future prospects of getting pregnant & also for how many days this blessing will continue. Kindly help on urgency. Thanks so much.