We just went through this... he had some slight wheezing that was "mild asthma brought on be allergies" so ryan is now on childrens claritin...... and a puffer a couple times a day. the danger in not treating it is it turning into something else. pneumonia, ear infection, whatever other unpleasant ailment comes from not treating when the illness is new. the ragweed right now is very high!! we moved from FL last december, so like your son, this is ryan's first exposure to "whatever's in the air in dallas in september/october" ya know??
this link has been helpful for us. you can view the allergen counts for different areas. http://www.aaaai.org/nab/index.cfm
hope he feels better soon!