What Causes Lower Abdominal Pain On Right Side?

my 13 year old daughter is having abdominal pains that are hurting her severely. it is near her groin area. her menstrusal cycle has passed and she describes the pain as severe and as if someone is stabbing her on her right side lower groin area. we have rested since 230 with a heating pad and she has been drinking plenty of fluids. she said the pain is still the same and is still bothering her. do i need to take her to the emergency room? please tell me.