As a medical oncologist, one of my specialties, I treated a patient with so called "fever of unknown origin". This was a 41 year old gentleman with extensive lymphoma, undergoing chemotherapy. His body condition deteriorated rapidly during chemotherapy and his complaints included restlessness, dry mouth, insomnia and significant weight loss. The mentioned symptoms progressed, and he developed a high fever. Needless to say, the first thing that came to my mind was that he had developed some sort of infection. He was hospitalized for nine days. Extensive workups (including many blood cultures and repeat CAT scans) failed to show any source of infection.
Unfortunately, modern Western treatment had probably made him more ill, as antibiotics and some of the anti-inflammatory medications cause nausea and stomach pain. I discharged him from the hospital and started him on traditional Chinese herbal remedy to boost and balance his yin energy. His fever subsided within days, and other clinical manifestations also improved very quickly. The point I am trying to make here, is that high fever is not only seen in people with yin energy excess, it may also be seen in individuals with yang energy deficiency. If an incorrect diagnosis is made, treatment not only is ineffective, it may make things a lot worse.