HI Thanks for posting your query to Healthcaremagic. Fever could be due to many causes but by far the most common cause is Infection . Infection could be due to Virus , Bacteria or Fungus. Infection could be anywhere in the body from head to toe. So we need to evaluate Where is the infection ? And whether it is Viral or Bacterial or Fungal Infection , as the treatment is entirely different for each . I advise you to get the following test done and revert back with reports. Complete Hemogram , Widal , Smear for Malaria, SGPT, SGPT, Ultrasound Abdomen pelvis, Blood Culture and Urine Culture Sensitivity. Hope this information was useful to you. Any clarifications feel free to ask .