Hello
Fever with rigors ,
low grade fever, leucocytosis ( mild degree ) with loss of appetite .
Evening rise of temperature are suggestive of following .
1
Typhoid fever as in one strain 1:160 is an indication of typhoid . Diagnosis can be confirmed by serology test .
2 Jaundice or
hepatitis is another reason which develops such type of symptoms . Diagnosis can be confirmed by blood examination for H B ASG for A , B ,C E .
3
Tuberculosis , as all indication are suggestive of tuberculosis . Diagnosis can be confirmed by Xray chest and C B C & E SR.
As you mentioned that leucocytosis is there ( although mild degree ) but it is an indication that patient may have infection .
Regular blood examination is very important in this case for T L C ( if elevation , danger ).
As you mentioned that patient is taking rociphen that only act up to certain limit .
Meningitis is another reason of such fever.
In my opinion deal according to above mentioned reasons.