Transcript for Mom Fights for Boy Who Can Only Eat 7 Foods
Now to the story of a 6-year-old boy allegic to nearly all foods. It's a rare medical condition. At first, he could only eat one food. Now, linzie janis has more. Reporter: A lot of kids are picky eaters. Tyler has a great excuse for only eating peanut butter and jelly sandwiches. The 6-year-old is allegic to almost everything else. As an infant, he was even allergic to his mother's breast milk. For the first four years of his life, he could only have baby formula. When did you first realize something was wrong? The main problem was when we started to introduce the baby foods. Reporter: What reaction did he have? Vomiting, sometimes 15, 0 times. He would lay there. He was lethargic. I didn't know what to do. Reporter: Doctors could not pinpoint the illness. All of the standard allergy tests came back negative. At 16 months old, he was referred to dr. Anna novak. She knew it was food protein induced entero-colitis. Reporter: If he's fed a food that he's allergic too, his body rejects it. It must be heart breaking. There's though words for when your child is that sick. Reporter: The doctor said he should go through food testing. He has to ingest the food to see if he reacts to it. Reporter: He made headway over the years. Today, he eats maples, macaroni and cheese, and pizza. We're going to have a chat, you and me. Tell me a story about some time when maybe there is food served at class and you couldn't have it. They had chicken there. All the kids were eating it. And I wasn't. How was your day at school? Reporter: Lucky, the prognosis is good.T goes away with age. It is hard at the beginning. You can get your child safe and healthy. Reporter: Now he can focus on the important things in life, like scoring home runs at hi little league games. For "good morning america," linzie janis, abc news, new york.
This transcript has been automatically generated and may not be 100% accurate.