What Causes Frequent Attacks Of Cold And Cough In A Toddler?

Hi Doctor, My 22 months old daughter catches cold and cough when season changes. It starts with a fever and then cough (dry and wet). She has been taking medicines like: Bricarex, Calpol drops, Calcerol sachet, Tixylix, Brozedex syrup. How to get her cured? Regards