Fever persisting for 20+ days despite antibiotics, with temporary response and nightly rise, is a classic presentation of Fever of Unknown Origin (FUO) that needs systematic investigation. Causes include occult infections (malaria, brucellosis, TB), autoimmune conditions, or rarely lymphomas â all need proper blood workup to rule out.
Next Steps
Get CBC with differential, ESR,
CRP, blood culture, malaria antigen test, Widal (repeat), urine culture, and
LFT done urgently. Consult a physician in person. Please consult me directly on Practo for a detailed evaluation.