Is Throat Infection Curable?

Dear Sir, My son age of 4.5 years, having frequntly problem of cold, fever. Often cold convert in cough and suddenly get throat infection where breathing problem and whistling comes. Normally pediatric give him Asthalin & Beclate inhaler and Ascoril D cough syrup. Our main concern is (1) small cold cough suddenly convert in throat infection and its take time to control. (2) is it curable? (3) this not effecting other body parts? Kindly suggest