There was once a family called the Stevensons. They had a little boy, only eight years old, named Tommy.

One night after a fun day, Tommy couldn't go to sleep. Something kept bothering him...

His mother tried helping him, but nothing made the stomachache go away. So, she decided to read him a bedtime story.

She began, "One bright summer day, The Robinson family went on a trip to the local amusement park.

They have a fun time riding rollercoasters, watching live shows and playing circus games!

When it was lunch time and everyone was super hungry, Jaime, the little sister, suggested to go for pizza.

"Good idea, honey!" said the mom.

Jaime's brother, Joey, exclaims, "Yay!" He likes pizza very much.

But after he ate a few slices, he started to feel funny. His tummy rumbled and grumbled weird sounds. His mom didn't know what was going on. She thought he simply ate too much.

The Robinsons continued their fun day after lunch. By the end of the day, they were walking down the street when Joey stopped and complained about his tummy again.

Why hasn't the grumbles and hurting gone away yet?

The Dad said, "Oh! Joey, maybe you are actually just hungry. Have a sandwich."

So, Joey ate again.

He took a look at his sister. She was eating her second batch of cotton candy. He frowned while realizing he hadn't ate any cool candy from the park. His tummy just hurt too much.

They got home and decided to write down everything Joey ate that day to see if a certain food bothered his tummy.

His mom searched her electronic tablet for some answers.

Joey sat down and thought about how he felt and what he had eaten throughout the day. Even many hours later, his tummy still hurt.

The list was short and simple, but as his parents looked at it more and more, they thought about dealing with the problem more seriously.

His symptoms were very strange and it wasn't the first time he had them.

Joey's mom decided to call the doctor.

"I think there is something wrong with his stomach, Doc." she said over the phone. "This isn't the first time he has complained about his tummy hurting after eating normal food."

Not long later, their family doctor came by to help Joey. He performed some basic tests and asked Joey questions about his symptoms. Joey wasn't scared or sad, just curious. He wanted to know why he was feeling this way and how to fix it. The doctor said he can help him learn the answer to both of those concerns.