For starters, do not let your son see that it concerns or bothers you! It could be a power struggle, it could be a reaction to his new brother, even if he appears to love him. My daughter loves her baby brother but she acted out regardless in odd ways. Just don't let him see a reaction out of you. It could be a phase, you can feed him nothing but those two foods, he will eventually get tired of it. Don't even offer your food, just that. Or, you can wait him out. Kids won't starve, they'll eat eventually. For my daycare girl who is the picky eater, I give her a plate of what everyone else is eating without a word (this was hard for me) and she doesn't get a treat unless she eats her lunch. Her parents will pick her up and feed her whatever she wants (which literally is all junk food, she hates anything of value). With my own kids, I would do the same only for every meal the same plate came out, they learned to eat it warm. One thing that helped me was to just not have the food in my house, that way I would open the cupboards and say, all gone! It caused fits, but fits are short term. Kids can only get hooked on what foods you give them access to. Only stock your home with nutrition quality food and food battles won't feel so hard. I'm sure you'll get lots of advice on this, I wish I'd of had it a few kids ago! Something important is to make sure he's having a good multivitamin every day. These years are years of odd diet for many kids. They have liquid drops, which my 17 month old loves but they stink, no clue how they taste, the chewables, and now gummi vitamins. He should be willing to eat one form, just call it vitamins, please don't call it candy!