Sweets and chocolate doesn't cause cough.

Eating chunk of chocolates produce large amount of saliva in child which might trickle in airways from nadopharynx to produce cough....so allow small pieces of chocolate at a time to prevent cough

Hello there.  I can understand your concern.  The history is very insufficient and very vague. If you think he gets it due to sweets and chocolates, then you can avoid giving him those. But i would suggest you get it checked out by a ENT specialist in person for further evaluation and management.  He will be able to help you. Best regards. Dr. Anil kumar jain. Bangalore.