The main heat generating organs of the human body are concentrated in the upper body, while the lower body has no heat generating organs. If you have a fever, it is likely that the upper body is hotter and the lower body is cooler. This is because generally when you have a fever, the peripheral nerves are not active enough and the blood flow is not particularly adequate, which leads to a slightly lower temperature in the lower body. The upper body is warmer because it is closer to the heart and has more organs that produce heat. It is important to observe the cause of the fever and the change in temperature. If the temperature is not particularly high, a simple physical cooling method can be used; if the temperature is particularly high, it should be treated with medication and further examination is required.