It does sound like croup. Not all kids will cough all the time with it, and it's usually only at night. But if he is having trouble breathing easily because the airways are narrowed, it will make him cough if he tries to take a big breathe. Definitely take him to a Dr if you can and get a script for some RediPred and Predmix, which are steroids that open their airways again and help them breathe easier.