Cancer is the mother and nurturer of the zodiac, and the body parts it rules are closely associated with mothering: the chest and breasts (externally) and stomach (internally). Because of their intense emotions, Cancer natives notoriously have stomach issues and their nervousness results in upset stomach, cramps, gas, ulcers, or severe digestive issues.
Cancers being so highly influenced by their stomachs also stems from the old saying “trust your gut.” They are the most intuitive sign. When their instincts alert them that something’s wrong, they can get immediate stomach aches that don’t go away until they know everyone is safe and the situation has been resolved. This is sometimes called a nervous stomach, and Cancer gets it a lot. They also get butterflies in their stomach—something that can range from mild to severe when they’re happy or excited about something.