The fever runs its course, the little one is perhaps uncomfortable for a while but eventually when the innate intelligence of the body has used the fever to serve its purpose, it will reduce it. The third situation is probably not seen too often. This is the small child who is brought in with no particular symptoms and shortly after an adjustment the child begins to manifest symptoms of being a sick little tyke. The fever-regulating mechanism was not working properly, only in this case, that malfunction manifested itself as a lack of fever when one is needed rather than a high fever when one is not called for. The difficulty is in the parent attempting to determine a beneficial fever from a harmful one.
Fever is a symptom.
We know philosophically that the innate intelligence will not elevate the temperature to a point that would be harmful. That would not be intelligent. For one person 104 may be in his or her normal range, for another it may cause convulsions. A patient's body, even though in adjustment, may pass that critical point due to limitations of time or matter in spite of the efforts of the innate intelligence to bring it down. I have never heard of a case of a child who was adjusted going into convulsions but in theory it is possible.