ETA - 100 flowers to you, Diane B. Your last paragraph is terrific - I couldn't have said it better...
Original:
Well, I'd get another doctor. Saying that a 3 (or 4, which is it?) year old kid will get tonsils out at 8 makes NO sense...
No more milk. Don't buy any. "Oh gee, honey, I'm sorry, but we're all out!" Put a small plate in front of him and a little bit of food. Sit there and ignore him and eat your food. Let him fuss. "Oh, you want down? You must be done. Off you go!" and put saran wrap over his plate. Continue to ignore him. Continue your dinner. He'll probably come right back in and whine for food. Put his plate in front of him with the saran wrap.
If you continue to do this, he will finally start to eat. But if you have milk in the house before you break this habit, he will continue to fight with you to get that milk. NO MILK IN THE HOUSE!!
The point is, you DON'T MAKE HIM EAT. Kids can only control 2 things in their lives - eating and toileting. That's it. He is controlling you with food.
A family member went through this with her son, only it was with peanut butter sandwiches. She tried and tried to get him to eat anything else and he refused. Summer came and she sent him to his cousins for a while. Instead of people paying attention to his peanut butter sandwich habit, they put regular food on his plate, and after they cleaned their own plates, they cleaned his too. They didn't want to "waste food", you see. Can you guess what happened then? Oh boy - he didn't like all those hands swiping his food! So after this happened a couple of times, he ate like a champ, beating them at their own game. When he went home, he was used to regular food again.
So stop it with the arguments. Just offer the food and ignore. Don't change any aspect of the food. He eats what was offered, that's it. If he doesn't, pretend you don't mind. Over and over until he stops begging for the milk.
I loved milk when I was little too. I'd drink the carton and then couldn't eat my lunch. My mom asked my teacher to only give it to me after I ate. And at home, my mom would do the same thing. Worked fine. Then again, I just liked milk. I wasn't trying to manipulate my parents...