This patient is a 12-year-old girl who was in normal state of good health when she developed fever several days duration?

Based on the information you have provided, it is not possible for me to diagnose the patient's condition. Fever can have many different causes, and in order to determine the cause, it would be necessary to obtain more information, such as the patient's medical history, symptoms, and physical examination findings. I recommend that you consult a healthcare professional for further evaluation and diagnosis.