What Causes Diarrhoea Along With Abdominal Pain?

My child 5 yrs old had watery motion almost 20 times a day, since last two days, with sharp pain in abdomen while passing motion, 2nd day I had given him normtetrogyl 5 ml for 2 days. It reduced and watery stool became normal. But on 2nd day the frequency increased again and he started passing watery motion, Should I continue normetrogyl or give him something else. I gave him ORS, probiotic and lactobacillus as well