Picky Eaters?

My BFF has a three year old son that only eats like every other day. He has gone 3 days with out eating anything. When he does eat, it it's the same things...canned Ravioli, ramen noodles (sometimes), tater tots with cheese or ketchup, mac and cheese and occionlly chicken nuggets only from Chikfila. He likes apple juice and that's it. Won't drink milk, not even chocolate or strawberry, no water. Will not eat nay type of vegetable at all, not even corn. I don't have kids, but I don't think it's normal. He will sit for hours looking at a plate of food and you know he is hungry. Dr. said that he is fine, nothing they can do and kids won't starve themsleves to death, he'll eat when he gets ready. I don't buy it. She tried Pedisure and he yelled that it was milkshake and threw the cup down. Any advice. My BFF just cries becuase he won't eat.