a tr mystery. Out why this little boy problem for a 3 1/2-year-old s Special formula. He simply can't eat any food. Linzie janis is following the story.1/2-year-old Reporter: Thanks. It's great to be... See More
a tr mystery. Out why this little boy problem for a 3 1/2-year-old s Special formula. He simply can't eat any food. Linzie janis is following the story.1/2-year-old Reporter: Thanks. It's great to be here. Doctors at the mayo clinic are trying to figure out why this little boy can't eat. So far, he's been surviving on a special formula.Neocate but now, even it is triggering a reacn. The 3 1/2-year-old michael gonzalez is allergic to everything he has ever eaten, except one thing. His parents say this prescription-only children's formula, neocate junior, is the only thing they have found he the digest. Tastes jennifer and tom gonzalez says michael was diagnosed with a re food allergy. Imagine the worst case of flu you ever had. Violent multiply that by ten. He knows that eating tastes good.Rted b and when he eats, he loves it. Until four hoursater. And realizes he never wants to eat again. It was a new Reporter: Four months ago, his parents say he had a violent reaction to that very formula that is sustaining his life. He started by being severely irritable. And then, he started vomiting. And that's when we figured out it was a new label.E Reporter: It coincided with manufacturer changing the packages. On the compa's website, nutricia acknowledges that some have had difficulties with the formula. Smells different. It says, we completed an exhaustive evaluation of the product. Mrs. Gonzalez bought older cans all tests confirmed that neocate junior unflavored has not been changed or altered. Wan it tastes different and smells different. It mixes different. And he kept refusing the bottles. Can Reporter: Mr. And f mrs. Gonzalez bought older cans of the formula othe internet. But they expire in october. We want our safe food back. Reporter: They've traveled to minnesota where a new team of specialists are working to solve the mystery, where nothing can be ruled out. You have to start from scratch. There's no an allergy?Arantee. Is there a structural or physical or anatomic problem? You really need a full team of experts or a multidisciplinary approach to get to the bottom of it. Reporter: Most children grow out of the condition by the time they are 6. Gives you but there's no guarantee. Jennifer gonzalez is worried about what her son will eat when let's hope he outgrows out. Time for a check I spoke with a spe who tolme that kids don't die from s disord becau they can back get the nutrients intravenously. It's not a long-term solution.Al it gives you a sense of how dire the situation is. Stomach flu times ten. Let's hope he outgrows it.
This transcript has been automatically generated and may not be 100% accurate.