We get the same thing with DS. I'm still trying to work it all out. It has gotten worse every year. He is nearly 6 and is now on a preventer. He had a cough for 10 weeks. He has allergies as well so he does sneeze a lot which makes it harder to work out asthma. He got to the point that he had little energy and was affecting his behaviour. So my advice would be to keep on top of it. I was reluctant to go down the medicine path but it was unavoidable.

DS is also allergic to dairy. It started off quite mild and it is quite full on now. I'm trying to eliminate but it is very hard when he is out with friends etc and there isnt an alternative. However I've seen an improvement already.