How To Treat Diarrhea,pain In Pelvic Region,abdomen And Back During Periods?

hey, im 17 years old and i just got my period today, and im having diaherra, pelvic pains lower abdominal pains mostly on the left side, and also back pains.. and i always got this the first day of my period.. is this normal?? is it supposed to be really painful, and i also took advil and it also did not help.. can u plz tell me what to do