Your body temperature is 39.9°C (103.8°F)?
The normal human body temperature oral (under the tongue) should be about 36.8°C (98.2°F), while the normal internal human body temperature (rectal, vaginal) should be at about 37.0°C (98.6°F).
Values of atleast 0.5°C above said temperature can be considered fever while temperatures of 1-2°C below normal temperature are known as 'Hypothermia' (body temperature too low).
Your body temperature of 39.9°C (103.8°F) is high and might be fever.
A temperature slightly above normal to a temperature of 100.4°F (38°C) is called a low grade fever and usually not a cause for worry unless it continues to rise. A temperature that is higher than a low grade fever should be monitored and a fever of 104°F (40°C) or higher can be dangerous and a doctor should be called immediately. A high fever can cause convulsions and delusions, especially in infants, children and the elderly.
A fever is actually one of our body's healing defense mechanisms. When we get sick and get a fever, our body is actually trying to kill what made us sick in the first place. The most common causes of a fever are illnesses due to a virus or bacteria. Since viruses and bacteria cannot live at higher temperatures, the body's immune system uses fever to stop the illness. In other words, that fever that makes us feel so miserable is actually trying to heal us by killing what is making us sick. For this reason, it is usually best to let a low grade fever run its course, unless there are other severe medical symptoms.