What Causes Cough, Cold And High Fever In A Child?

Hello Doctor, Good afternoon!! My son is now 4.5 yrs old having a weight around 21 kgs. From yesterday, he has acute cough and having pain in his throat. After consultation with doctor, we have started to give him Azithral 200 mg and maxtra syrup prescribed for 5 days. He has also high fever (around 100-102 c).He also loosing his appetite. Is this having any relation to his tonsil or simply due to cold & couugh problem? Please advice. Regards S Rakshit