Hi A.,
My oldest who is now 7 used to get croup almost everytime she had a cold until she was about 4-5 and then she out grew it. You have to be careful with croup, it worsens at night, and you need to watch their breathing. We had to rush her to the ER one night because her breathing had become so labored. The doctor can recommend what medicines are best, but we only used them when her breathing got scary. If your childs breathing isn't that labored at night, then no need to worry, it will clear up. I know how scary that "barking" sound can seem, but its only scary when they can't breath. Usually, if you run hot water from the shower in a closed bathroom for about 5 minutes, the humidity will help open up their airways, and get rid of some of the congestion. Just sit with them in the closed bathroom and read a book for a few minutes. Also, a quick trick that would work for us at night, would be to take her outside where its chilly. Breathing in the cool air seems to help as well. Croup usually lasts as long as a typical cold, about a week. Hope this helps, and best wishes!
C. Helm