Wheezing from the lungs is a symptom of asthma. Sometimes, it is possible to hear a sound that is like wheezing from a nasal obstruction. I would recommend speaking with your physician before attempting any home remedies.
If your son is wheezing and doesn't have an official diagnosis of asthma or allergies, you need to take him in to be seen...either at pediatrian's office or the ER. It could be related to things you stated, but it could be something much more serious like pneumonia, RSV, etc....