As you said your child is getting recurrent fever
since 2012 , are these episodes are associated with any of cold
, throat pain or ear pain? Is there frequency of urination ? If these are there they will suggestive of some focus of infection. Once you go for investigations like CBP,MP,Urine for C/S and if these are normal go for furthur investigationl like collagen
profile etc after consulting your doctor. And maintain a temperature chart by plotting every day temperature on a paper during these episodes so that the pattern of fever will give clues to the diagnosis.