If a child is experiencing a persistent cough, it is important to consult a doctor, especially if the child is under 2 years old. If the child has a fever that has lasted for more than 2 days, it is advised to seek medical advice. If the child is under 1 year old and has had a fever for over 36 hours, it is also recommended to consult a healthcare professional. For infants under 3 months old, immediate medical attention is necessary if they are experiencing any symptoms.