Hi thanks for asking question Here are few possibility in your case. 1.First if stool is watery and look like rice watery white color then it could be by vibrio cholera.stool culture done for it.stool may show motile bacteria with darting motility. Antibiotic needed for it. 2.Second it could be parasite infection .for that first stool examination done that might show egg of ameba or tapewarm segments.for amebiasis metronidazole needed and for tapeorm anthelmetic drug given like that of albendazole. 3.Third this could be by E.colitis or staphylococci toxin like bacterial infection causing watery diarrhea.stool may reveal pus cell.stool culture helpful.antibiotic needed. If still no benefit ultrasound or endoscopic examination needed. I hope my suggestion will be helpful to you