My 4 mth. Baby has a cold or allergies. At times he has a coughing spell, how can I control the coughing? I'm using a cool mist humidifier/baby vicks.

No Medicine BUT..... There are no medicines for cough in a four month old but if your baby has cold symptoms with a persistent cough the possibilities are numerous including pertussis so i think it is very important that you visit with your pediatrician now.
? Feeding`. If bottle fed, any form of cow's milk formula can do this. Try nutramigen. If breast fed, then see your pediatrician.