Fever on and off first Widal negative and after Widal 1:160 taken antibiotics then Widal 1:40 but still fever morning up to 9am it is below 98.6 and after 11am it is increasing to 99 and at afternoon it is going to 99.6 and at evening at 8pm it is coming to normal during this I am having headache ,fever ,from 40 days .Which tests are to be done now ,what is the problem now plz give suggestions sir