Hi thanks for asking in Healthcare Magic. Stools test will reveal the type of infection (bacterial or protozoal) . The most common causes of diarrhea are bacterial and protozoal (amebiasis or giardiasis) infections. Norflox is effective in diarrhea due to bacterial infection and Tinidazole (TZ) is effective in protozoal infection. But if does not respond to both drugs, then it could be due to viral infection. Antibiotics can also cause watery diarrhea. Drugs like Loperamide are given to reduce the frequency of diarrhea due to viral infections. Since he is prone for dehydration due to watery diarrhea you should give him oral rehydration fluids (ORT) like Electral. If the dehydration is severe then he will need IV fluids. Bland diet like bread, banana, yogurt and curd rice will help. Probiotics are effective in reducing the intensity and frequency of diarrhea. However, if diarrhea persists then you should visit your treating Dr to rule out other causes like ulcerative colitis, celiac disease and irritable bowel syndrome. i hope this is helpful to you.