Fever results when the body's thermostat is reset higher. If the temperature is set higher, the body feels cold and may send out a signal to the muscles. The muscles begin to shake repeatedly. This involuntary shaking, or chills, makes body heat that helps produce fever.
Chills can be constant for up to one hour, or they can come and go.
Fever is a helpful response to infection. This helps to uncover other signs and symptoms. Fever by itself is not very useful in pinpointing a cause. Keep a temperature log. A rigid neck.