Whatever history you have provided, points towards Infective cause.
It could be wheeze associated, WALRI ( Wheeze associated lower respiratory tract infection)
Change is season could be the factor. I guess, your child must be visiting day care, and there is gets exposed to infections.
Make sure you improve his immunity with help of immunity boosters and with good diet.
Such recurrent infections warrents one Chest Xray and Blood Counts.
Kindly visit your pediatrician and seek his help.
Health Tips
Never use antibiotics without your doctors advice