CRP is
C reactive Protein. It is a kind of protein produced by
Liver during Infection or Inflammation.
It is indicator of not only Infection but also something called as Inflammation as well. And ,though it is important in ruling out infection, it is not read only as single test. It must be used with other counts like CBC and Blood culture etc.
As you are saying, it is constantly elevated, then kindly get ESR done.
Is ESR is also elevated, and there is no infection then I suspect some kind of Inflammation.
Better you visit your pediatrician, as he is in better position to do whole body examination and comment,
Hope this helps.
Happy Parenting