Baby's Growth Issue

My Son was IURG 29 weeks, 1.3Kg when born, now he is 1.6years, 10kg, fully active, but physically weak and eating average. He has issue of Anemia, since birth, latest CBC was on 07/02/18, WBC-15.15, HB-12.3, RBC-4.98, HCT-35.8, MCV-71.9, MCH-24.7, %Neut-11.3,%LYMP-22.1,%MONO-70.9,#LYMP-10.74, he is taking iron drops, I want to know what specialist (hematologist or pediatrics or else ) will treat this issue. Please advise me. Thanks