Intestine

"The intestines are a long, continuous tube running from the stomach to the anus. Most absorption of nutrients and water happen in the intestines. The intestines include the small intestine, large intestine, and rectum.
The small intestine (small bowel) is about 20 feet long and about an inch in diameter. Its job is to absorb most of the nutrients from what we eat and drink. Velvety tissue lines the small intestine, which is divided into the duodenum, jejunum, and ileum.
The large intestine (colon or large bowel) is about 5 feet long and about 3 inches in diameter. The colon absorbs water from wastes, creating stool. As stool enters the rectum, nerves there create the urge to defecate."

Baby colic

Baby colic is a condition in which an otherwise healthy baby cries or displays symptoms of distress (cramping, moaning, etc.) frequently and for extended periods, without any discernible reason. The condition typically appears within the first month of life and often disappears rather suddenly, before the baby is three to four months old, but can last up to one year. One study concludes that babies who are not breastfed are almost twice as likely to have colic. Epidemiology suggests that chocolate, brassica, onions, and cow's milk are among the foods that a lactating mother may need to avoid.