My father has been having fever from 30 days. Morning the temperature is 98-99°. By evening temperature rises to 100-101°. Initially he took dolo but later that also isn't reducing fever. There is no other symptoms, his chest x rays is clear, blood reports are normal, also tested for tb which is also normal.  He is very tired all the time. Unable to find the problem. Already visited 2 senior doctors couldn't come to any conclusion. Please help