Coughing and snotty noses are diseases of the upper respiratory system. Pneumonia is a disease of the lower respiratory system. Although snotty noses and coughing can also be present when an animal had pneumonia, they usually aren't a sign of pneumonia.
Signs of pneumonia are droopiness, rapid breathing, and lack of appetite. If it is within a month of sale time, call your veterinarian. The drug to use is Naxcel, which is quite effective against pneumonia and has no withdrawal time. If the fair is more than a month away, use the long acting tetracycline as described above. Pneumonia is a life threatening disease. Early treatment is important.