I have an fever of unknown origins for 13 days. we suspect it's some kind of infection. standard tests have been done (blood test for viruses etc), chest x-ray. what other tests can i discuss with my gp to find the root cause of my mystery illness?

Specialist: Although true fevers of unknown origin are considered by some to be fevers of 3 weeks duration that are undiagnosed while being tested in a hospital or as an outpatient for at least 2days, I recommend that you consult a specialist in infectious diseases for evaluation at this time. Appropriate and thorough testing will be done. Many such fevers turn out to be from noninfectious causes.

FUO: Is considered to be after about 3 weeks, time at which most lingering infections should fade away. Among causes for FUO, autoimmune disorders, malignancies and drug induced are among the most common.