question: HiMy son is 13 - for the past 6 months has been looking tired with dark circles around his eyes.  For the past 3 weeks he has been very tired, with a constant headaches at the back and top of his head, lower appetite.  He is usually very active, lots of sport, and large appetite for healthy food.  Blood test done - low in white blood cells, low in iron.  WBC count repeated today at my insistence - I have been informed it is probably an infection and needs to work its way of of his system.  What should he be testing for if his WBC count remains low?Thank you