Hi...my Son Has Been Sick For The Last 10 Days

Hi...my son has been sick for the last 10 days with up and down fevers and chills and a few night sweats thrown in there too. We got his bloods done and they came back with high neutrophils(13.9x10E9/L) and high moncytes(1.3x10E9/L) and low haemoglobin and PCV. Whatever it is does not seem to be going and the Doctor can't find what might be causing the infection...should I be worried about it being anything more serious?? Thank you.