What is revealed as the cause of Freddie's upset stomach in the nonfiction book, One Child?

When Sheila covers rabbit poop in paint so that they look like M&M candies, Freddie believes tham to be the real thing and eats the rabbit droppings. Freddie's mother brings the issue to Torey's attention after he comes home several days in a row with an upset stomach, and neither Freddie's mom nor Torey are able to immediately recognize the "candies" as poop. Several days later, Sheila admits that she was painting the rabbit poop to use in an Easter mosaic.