What Causes Painful Bleeding During Periods After Taking Premolut N?

hi...i have prescribed, because of delayed mensturation, to take promolut n 2 pill for just a day, 2 or 3 days before my periods, i have experienced painful mensturation with little bit of bleeding after using this. doctor said that i have harmonal problem, so she is prescribing me promolut n, so, what you suggest for me???