Thanks for your query.
I understand your concern.
Repeated respiratory infections are common till 6 years of age.as child gets cross infection from peers at school or while playing.
Most of the times it is viral or allergic in nature and settles in few days with symptomatic treatment.
Antibiotics are to be given only if bacterial infection is suspected.
Since you have mentioned that your child is otherwise active so t
here is not much to worry.
I suggest you to give him good nutritious diet to boost his immunity.
Stop all kind of junk food items including chips,candies,fried items.
If symptom persist you can get allergy
test done.also go for Xray chest,CBC,ESR
after consulting your pediatrician
Wishing your child good health.