Hello and welcome. Unfortunately postinor comes with numerous accompanying side effects like menstrual irregularities, inter-menstrual bleeding, abdominal and/or back pain, weakness, etc. So the only thing you can do now is to make sure you are more careful during sexual contact the next time so she doesn t have to experience this again, and just be patient and wait until her next period comes which should help regularize her cycle and symptoms. She can also take medications like dicyclomine hydrochloride for the pain and abdominal cramps. Best wishes.