5 Year Old Coughing - Multiple Pediatrician Visits no help

Anyone ever experience their child coughing at night immediately after falling asleep for weeks now, will cough pretty much every 10 mins or so with brief 1-2 hour periods of no coughing. 

Paediatrician says he’s fine and is likely just battling a cold. 

During the day he’s his normal self, hardly coughs, no runny nose or other cold symptoms.  Eats and plays well like his normal self. 

Have tried a ventolin puffer (orange and blue) as per the doctor. 

Have tried cutting out dairy. 

Have tried keeping him upright, sleeping in other rooms (living room, basement)