😭😵 I'm going crazyyyyy!!!

My almost 4 year old (in January) first child ... has his days where he will eat and than days he wont eat anything and be on milk. I'm confused is this normal..?

He will ask for something ill make it and than he will throw a fit and not eat it... he does this through out the day am I alone anyone else have a picky eater I'm going crazy... ( example he will ask for a sandwich I'll make it and he wont even touch it.. he will ask for cereal and wont touch it)

I have a younger baby and he isnt like this at all he eats and will even take his older brother food. I wish they werent picky makes me think he is hungry and doesnt know what to eat (my oldest).