She's 4 and having high fevers every month for 3 days long.no symthoms. i'm worried?

Periodic fever: Children and adolescents with a few consecutive days of fever every month for many months, say at least 6, may not have a series of viruses, but a periodic fever syndrome. This is a tough diagnosis to make and requires keeping records of the fevers and any associated symptoms. Fewer months, more likely to be viral. Fewer symptoms, less likely to be serious.