I’m thinking it’s your Vagus nerve - it’s one of the the cranial nerves - running from the brain stem to the colon.
“The sensory functions of the vagus nerve are divided into two components:
Somatic components. These are sensations felt on the skin or in the muscles.
Visceral components. These are sensations felt in the organs of the body.
Sensory functions of the vagus nerve include:
providing somatic sensation information for the skin behind the ear, the external part of the ear canal, and certain parts of the throat
supplying visceral sensation information for the larynx, esophagus, lungs, trachea, heart, and most of the digestive tract
playing a small role in the sensation of taste near the root of the tongue
Motor functions of the vagus nerve include:
stimulating muscles in the pharynx, larynx, and the soft palate, which is the fleshy area near the back of the roof of the mouth
stimulating muscles in the heart, where it helps to lower resting heart rate
stimulating involuntary contractions in the digestive tract, including the esophagus, stomach, and most of the intestines, which allow food to move through the tract”https://www.healthline.com/human-body-maps/vagus-nervehttps://www.medicalnewstoday.com/articles/318128.php
“Other vagus nerve effects include:
Communication between the brain and the gut: The vagus nerve delivers information from the gut to the brain.
Relaxation with deep breathing: The vagus nerve communicates with the diaphragm. With deep breaths, a person feels more relaxed.
Decreasing inflammation: The vagus nerve sends an anti-inflammatory signal to other parts of the body.
Lowering the heart rate and blood pressure: If the vagus nerve is overactive, it can lead to the heart being unable to pump enough blood around the body. In some cases, excessive vagus nerve activity can cause loss of consciousness and organ damage.
Fear management: The vagus nerve sends information from the gut to the brain, which is linked to dealing with stress, anxiety, and fear - hence the saying, "gut feeling." These signals help a person to recover from stressful and scary situations.”