Talk to Pediatrician on Iron And Calcium Deficiency

Hi! My son is 2.5 yrz old he has weight 7 kg (bkrn time wght 2kg) He is short heighted with very low appetite. He is overall active but looks so skinny and younger than his age group children. If he eats some food like oranges etc it doesnt absorb in his body and he passed chunks in his poop. He has Haemoglobin deficiency as well. He doesnt take any kind of mother or formula milk. No flavor milk he takes. Kindly help. Thank you