My father has been struggling with high fever , chills and shivering since September 9 and the results for dengue, malaria, Tuberculosis,
AIDS all came out negative and even there's no infection on his blood. The doc that has been treating him too couldn't find out the root cause of this fever. And it's going to be a month since he has been admitted to hospital with no definite results or cure. Could anyone tell me what this could be? His fever only comes at night and during daytime it's kind of normal