It happened to us and I'm sure it has happen or will happen to you, too. We didn't read a label and fed something we thought was safe to our daughter. It read "Made in a facility with nuts..." Oh, no. We hoped there wouldn't be a reaction, but she had a messy, messy diaper shortly after eating. And it took her little tummy about a week to get back to normal -- she was getting over a cold at the same time, too.
I worked as hard as I could to get as much fiber in her as possible: beans, cereal, craisins, raisins, fresh fruit, yogurt, etc. But what also seemed to help was sprinkling in a little baking soda in her water. She doesn't like juice, but she drank the baking soda water. It is an antacid, and I think it's much safer than feeding a toddler "medicine." Just a suggestion to anyone who has a little one with tummy problems.
A little update
4 years ago