I would definitely get him in to see an allergist. I'm sure you know the Xopenex is an asthma medication. I use it in my nebulizer. The Singulair is used for both allergies and asthma. I am 56 years old and was diagnosed with severe asthma about six years ago. I did have my esophagus and a hiatal hernia repaired because they thought the GERD was triggering some of my asthma attacks. So, I can also relate to the GERD. Have you ever noticed if he starts coughing not long after he eats a meal? If so, this may be the GERD triggering the cough. You probably don't even want to get me started on cigarette smoke. You are doing the right think by keeping him as far away as possible the cigarette smoke, even outdoors. People (smokers) just don't have a clue what it does to those of us with respiratory problems. Perfume is a real trigger for me also, I don't know if they have thought of that. My daughters and all my friends have learned not to wear it around me.
I am serving on a committee in the city where I live in KY to get a Clean Air Ordinance passed. I hope we are successful.
If I can answer any other questions, please feel to email me.
Take care and good luck with that little boy!