I have always had an asthma related cough. I don't get any wheezing, but i do get a cough that is only relived by asthma medication, so it is possible that's what is causing his cough. My cough is always worse at night when lying down, so i prop myself up on pillows, raising the head of his bed might help....

I don't think you should give ventolin without speaking to a dr though. Even though it is widely available, i think it is super important to discuss the possibility of asthma with your dr first.