My Son Is 3 Years Old And His Weight Is

my son is 3 years old and his weight is 12.5 kg. he has cold, cough and high fever. my doctor prescribed him crocin ds whenever fever is there, mucorex-dx 3ml twice and swich 100 mg 3.5 ml twice. I start this medicine 3 days before but even now fever is around 101 F. how long will it take to recover him properly.