27month boy stop formula

I really feel you on this, it must be so worrying especially after he just recovered from a lung infection. Sometimes after a bad illness, little ones go through a phase where their appetite and preferences change quite a bit, so it may take some time for him to want milk again. You could try offering small amounts in different ways, like blending it into a smoothie or porridge, just to keep his nutrition going while he adjusts. That said, since he had a lung infection recently and now is refusing milk altogether, it might be good to bring him to see his PD just to be safe and get some proper guidance.