Thank you for your query,
Usually there are types of fever in different infections.
Like intermittent fever
in which fever will come on and off such as in viral or malarial fevers and upper respiratory tract
Continuous fever like some viral fevers.
I advise you to go for basic investigations like CBP, malarial parasite, widal test
and CUE to know any infection after consulting your Pediatrician
Hope I have answered your query.