Suggest Remedy For Chronic Cough Post Bronchilioitis

My 4 ye old son has been coughing non stop since last night all day at school and tonight. It is a dry cough with no productive sputum.
He had bronchilioitis per urgent care do about 10 days ago. He does have clear runny nose and looks exhausted. I have given Claritin, Benadryl and dysulum for cough, and .5mg of melatonin to promote sleep but he continues to cough. Please help with suggestion of what this could be. YYYY@YYYY