Viral Croup: This is the most likely diagnosis given the symptoms of cough, flu-like symptoms, and the characteristic croup cough (often described as a barking seal). The red dots on the face could be due to the forceful coughing associated with croup.

Influenza: Given the flu-like symptoms, influenza is a plausible diagnosis. It can cause cough, fever, and other respiratory symptoms.
Adenoviral Infection: Adenoviruses can cause a range of symptoms including cough, fever, and rash, which might explain the red dots on the face.
Respiratory Syncytial Virus (RSV) Infection: RSV is a common cause of respiratory illness in young children, often presenting with cough and other flu-like symptoms.

Epiglottitis: Although less common, epiglottitis is a serious condition that requires immediate attention. It can present with severe cough, difficulty swallowing, and in severe cases, respiratory distress.
Pertussis (Whooping Cough): This bacterial infection can cause a severe cough, often with a characteristic whoop sound, and is particularly dangerous in young children due to the risk of complications.
Pneumonia: Bacterial or viral pneumonia can present with cough, fever, and other respiratory symptoms. It's crucial to consider this diagnosis due to the potential for severe complications.

Kawasaki Disease: This rare condition can cause fever, rash, and other symptoms. Although it's less likely, it's a diagnosis that should be considered due to its potential for serious cardiac complications if not treated promptly.
Tuberculosis (TB): While rare in many areas, TB can cause chronic cough and other respiratory symptoms. It's essential to consider this diagnosis, especially if the child has been exposed to someone with TB or has recently traveled to an area with high TB prevalence.