Fever means illness or infection.
Tylenol or Motrin, does NOT 'cure' the illness/infection. It only TEMPORARILY provides help for the discomfort.
If the person is still ill... the fever will return.
Your child is also tired. He is ill.
Some illnesses, are only fever.
My kids have had that. They were sick. And the fever was present, in varying degrees, until they were no longer sick.
Or fever can be an indication of even a urinary infection.
Or of an illness coming on.
Watch him closely.
Take his temp often.
Keep him hydrated.
Have him sleep whenever need be. Sleep... helps the body to fight off things.
How old is your child?
Sometimes with fever, the child will have a headache also. But a young child cannot say exactly "I have a headache" if they are very young.
Or fever can also cause chills or them being very hot.
If the fever gets too high, take him to the ER or Doctor.