What Causes Abdominal Pain And Diarrhea On Taking Bigomet During Pregnancy?

I am few days pregnant woman in the age of 40yrs. Since, there was several miscarriages this time pregnancy doctor recommended 500mg of bigmet tablet twice daily. While taking I am getting lower abdomen area pain & starts losemotion. This happened in every take. Is it something related to protect from the threat of miscarriage? Kindly advise urgently