This is definitely a fever of unknown origin by definition. Have you taken a Chest X-Ray- PA view? I need to know detailed history of fever and any other symptoms, reports and medication history.
Next Steps
You may consult me online at Practo.
Health Tips
Make a temperature chart 4 hourly. Light meals at regular intervals. Plenty of fluid intake. Tablet Paracetamol 650 mg SOS after food.