My 22mo has had a mucousy cough, mostly during naps or at night for 2 wks. otherwise he's energetic and happy. what's the prob? and, should i worry?

Sinusitis: If your child had had a cold before the cough began, he may have a bacterial sinus infection. When he lies down the sinuses are draining down his throat and will set off the coughing. During the day there is less drainage and therefore less coughing. The original cold is over so his behavior is otherwise back to normal. See your doctor.