Sick 4 yo high crp +esr

He has been to the doctors three times he has a cough fever for 5 days on and off highest being 104 he tested negative for pneumonia, strep , flu , rsv and covid . They keep saying virus but juat received these high indicators on my chart his cbc is normal except for a high rdw he is eating ok drinking well playing jumping only time he is a little down is when he gets fevers they also did mono test one of which came back negative any ideas it has been a long week I need help any recommendations should i ask for further testing if so which one