9 year old with WBC of 3.9

My son startEd breaking out in hives Sunday night ( when ever he gets sick he will break out with hives usually on his stomach and back, not a tun just speratic) Monday his stomach and back were covered in hives, had a 101.5 temp. A couple hours later the temp came down on it's own to 99.4. That night he broke out in hives all over his legs, stomach, chest. Tues his temp was gone but now had hives on his arms and hands also. I took him to his dr who ordered a CBC
His WBC was 3.9 HGB 12.5 PLTS 244 Neutrophils 38 and 1.5.
His dr said that his WBC was probably low because he is fighting a virus. He now has a cough.
His ANC is 1440 which seems kinda low. what do you guys think is going on?
Thank you