My Son ( Age - 2 Yrs 11 Mths &

My son ( age - 2 yrs 11 mths & weight - 16 Kg ) had fever from 29 Aug to 3 Sept ( 6 days). After 10 days his body temperature was slightly warm... On 16 Sept his temp Crossed 100F & he got fever again. After consultation with the Dr. I give him P-250 & Fricium 5mg & Taxim O Forte dry syrup. The fever is continuing upto now with a break of 4hr/8 hr/12 hr. Now he is in stuffy nose condition and also sound sleep....
What is the reason of getting in fever again N again ?? Is there any fear?? Now what type of diagnosis should I do????