Monthly fever

Jessie

Hi guys! I plan on going to the pediatrician on Monday but I’m wondering if anyone ever experience what my son has. Since November he randomly gets a high fever (104) once a month with absolutely no symptoms. I took him to the doctor last month for the same reason and they tested him for Covid and the flu. All negative. The fever will last a day or so and then he’s fever free for a month until it happens again. This morning he was completely fine, we went to the science center and he played al afternoon. When he woke up from his nap I noticed he was warm checked his temp and it was 104. I feel like something has to be causing those