Community medical question

My brother fever is not getting down its 5th day doctor give medication and said its malaria first 2 days with injection fever go down but on 3rd day it becomes 103 with medication it becomes 101 but after 1 hour it becomes 102 or 103 but now it becomes 104 doctor said just take calpol or paracetamol when temperature get down we give injection but am too much worried why temperature is not going its 5th day now