Since the runny nose has persisted for more than a week without improvement, it is advisable to consult a paediatrician to rule out an allergy or a possible secondary sinus infection. Do not continue decongestant drops like Coriminic without medical advice, as prolonged use may sometimes worsen nasal blockage. You can use saline nasal drops to gently clear mucus and provide comfort. Ensure your child stays well hydrated and gets adequate rest. Seek medical advice promptly if your child has a fever, a persistent cough, or worsening symptoms.