** 1. It could be possibly diagnosed as PUO [pyrexia of unknown origin] due to . duration of fever more than 3 weeks. . failure to reach a provisional diagnosis after one week of Investigations. 2. Do check with Neutrophil count, blood sugar,Thyroid Profile. 3. other Common causes to look out are: Drug fever, faulty thermometer, factitious fever, Extrapulmonary Tuberculosis (as chest X-ray is normal), rheumatic fever, kala azar, Vasculitis, as Sonography came normal thus Amoebic liver abscess can be excluded. PS: Success in diagnosing PUO rests on meticulous history taking (with special reference to family, occupational, and recent travel history), and careful physical examination.