Fever and stuffy nose with full of mucus

She is 8 year old.Having cold & fever. Fever varies between 99.3 degree to 100.4 degree from 4 days. On 6th Feb, Doctor prescribed syrup calpol 250 ( 6 ml when temperature is above100) and Cherrycough Syrup twice a day. Not improved. Then we again went to doctor on 8th Feb and           Doc prescribed Advent Forte 457 (5 ml twice a day for 5 days) Calpol 250 ( 6 ml when temperature is above 100) Cherrycough Syrup 3 times a day 5ml. She is improving and fever decreases when Calpol is also given along with antibiotic otherwise fever will remain in same above range(99 to 100.4) so no affect without Calpol. My question is why to wait for fever to reach 100 why can't we give calpol along with antibiotic in remaining 3 days for better and quick result. Symptoms are no sneezing, no coughing, no loose motion, no vomiting. Only having persistent fever with stuffy nose white thick mucus. Is there any harm if we give calpol when temp is below 100? Is it right prescription? Please suggest.