The word "churn" means to move around violently, normally in a circular rotation. This does not mean the stomach is literally churning, but describes how the woman, representing Jerusalem, feels. Alternate translation: "my insides ache" or "my stomach hurts" (See: [[rc://en/ta/man/jit/figs-metaphor]])
Here the woman, representing Jerusalem, refers to her "heart" to emphasize her feelings. Alternate translation: "my heart is broken" or "I am extremely sad" (See: [[rc://en/ta/man/jit/figs-synecdoche]])
Possible meanings are 1) "inside the house, everyone is dying" or 2) "and inside the house the dead people are kept" (See: [[rc://en/ta/man/jit/figs-explicit]])