Croup. Croup is an acute infection, not chronic. Croup can be severe the first 2-3 days then slowly gets better. Use a humidifier, mist up the bathroom, take your child out in the cold air. You said it won't go away, how long has he had it? Your child may have something else. Schedule an appointment with your child's doctor.
Croup? Croup is like barking make sure he is not asthmatic. How old is he? Try opening the hot shower for moist steem, push fluids. Benadryl (diphenhydramine) is a cough suppressant or ask your dr for his opinion.