Frequent loose motions in a 14-month-old that are not improving despite treatment need proper re-evaluation, as most cases are due to viral or dietary causes, and strong antibiotics like Colistin are only useful when a specific bacterial infection is confirmed, not routinely. The most important step is to prevent dehydration by giving ORS, continuing normal feeding (including breast milk), and using zinc as advised. Since symptoms are persistent, your doctor may recommend stool tests (to check for infection or parasites), review diet (for lactose intolerance or food-related diarrhoea), and assess for conditions like Persistent Diarrhea. Avoid self-medication and unnecessary antibiotics, and seek prompt pediatric consultation, especially if there are warning signs like reduced urine, weight loss, fever, blood in stools, or lethargy, so that the exact cause can be identified and treated appropriately.