My Son Has Been Coughing From A Cold (we Assumed)

My son has been coughing from a cold (we assumed) for over 2 weeks now. Occasionally he vomits but it is mostly clear or color of whatever he eats. He has just been diagnosed with a mild case of pneumonia in his left lung. He has been prescribed antibiotics and a stronger cough suppressant. My son is 37 years old. Is this just the flu or influenza?