The pit of your/the stomach - Idioms by The Free Dictionary
the pit of your/the stomach
pit of one's stomach
Fig. the middle of one's stomach; the location of a "visceral response." I got a strange feeling in the pit of my stomach when they told me the bad news.
the pit of your (or the) stomach an ill-defined region of the lower abdomen seen as the seat of strong feelings, especially anxiety.
the pit of your/the ˈstomach the bottom of the stomach where people say they feel strong feelings, especially fear: He had a sudden sinking feeling in the pit of his stomach.