Fever means increased body temperature. Different people have slightly different body temperature. So "normal" body temperature is not a point but a range, which is 36.5-37.5C or 97.7-99.5F. Loosely speaking, if your body temperature is above this range, you have a fever. Acute fever is fever that is present for several days. If you have chronic fever, use Fever (chronic fever) instead.
By answering questions about your condition, you can find the causes.