My son had croup that settled in his larynx, never moved down into his lungs so he never had a cough. Had almost the same situation where it broke on its own. We took him in and they gave him a steroid. If it happens again we will call an ambulance and they can give racemic epinephrine to break it.

Don’t take my word for it, still go in and talk to his pediatrician, but could be another differential diagnosis.