Porter [not] eating cheese

We have a long list of things he will [not] eat. Cheese, hamburger meat, ravioli, and fish are just a few. There are a lot of foods that never make it as far as cheese. He gags if you touch most things to his lips. He never even tastes them before he gags. Right now the only thing he will actually open his mouth for and eat enough of it to count is yogurt and nutrigrain bars. He had that for breakfast and lunch today. For supper he had half of a little thing of applesauce. He was offered macaroni and cheese, meat sticks, ravioli, cooked apple bits, puffs, and cheerios. He wouldn't even eat the puffs, which is usually our Plan B. Oh, and I forgot about cheez-its. He loves them and will put them in his mouth and suck on them until they are soggy enough to chew and swallow. I know this stage will pass, but it sure is frustrating.