SevereLower abdomen pain diarrhoea twice

My daughter is 23yr old, a yr ago she had upper abdomen pain and was given medicine for acidity and was under pagero40 mg and mucaine gel for 3 months ,her pain subsided,2months back again she had pain and was again on the same medicine and kept ok.2 weeks back she had pain after food in her lower abdomen..3days back she had severe lower abdomen pain with mouth sore and 2 episode of diarrhoea...she was referred to gastroenterology and there ultrasound of abdomen for suspected appendicitis,stools and urine test taken...normal results with slight polycystic morphology changes in both ovaries,we consulted gynaecology and she told no problem...gastro Dr. Prescribed Cizaspa and sompraz40,She took only 1tablet each and her pain subsided completely,now she's ok.My question is what would have been the cause of pain,since she in hostel and taking outside food ,i wanted to know the reason behind the severe pain ,now she is not under any medication.no mouth sore too.kindly reply.