Fever in between 99 to 99. 8. Fever!

At First widal o&h 1:40 fever in between 99 to 99.8 ,after 5 days ,widal o& h 1:160 antiboitics taken for 14 days like gudcef, azithromycin,ornio,moxinow,after 10 days Widal o&h 1:40 but fever pattern is btnn 99 to 99.8 during thypoid also ,tests done like thyroid normal,bp normal,esr 30,crp 6,smear for mp negative,tc 12900,urine normal,chest x-ray normal,mantou normal,USG abdomen normal,fever from 50 days ,which tests are to be performed.now fever is present in morning after 8am to evening 9pm ,having headache,now taking doxycycline antibiotic,today blood test done ,hb 15.5,trbc 6.3 Millon's,platelet cont 1.65lakhs,twbc 5600,esr 25,pcv 60,tyhidot igg& igm negative,what is the reason for fever from morning at 8am it is 99 and in afternoon in between 99.4 to 99.8 and evening after 9pm  it is 98.6,blood culture done no gram positive or gram negative bacteria observed in smears ,no enteric bacteria,or pyrogenic bacteria seen in culture .what is reason for this fever