If you feel a fever on your forehead, it may be because of a cold, fatigue or irritation. If it's only a slight fever, you may not have to worry too much. However, if you feel that your forehead has a fever for a long time, or the degree of fever on your forehead is obvious, I suggest you consult a doctor or do some basic physical examination to rule out possible health problems.
As for Feng Shui, it is an ancient traditional culture in China. It believes that people's fate, health and wealth can be improved by adjusting their living environment and lifestyle. There are many laws and methods in Feng Shui, but not all of them are scientific.