Charles Ellicott Commentary 2 Chronicles 21:15

"and thou shalt have great sickness by disease of thy bowels, until thy bowels fall out by reason of the sickness, day by day." — 2 Chronicles 21:15 (ASV)

And thou shalt have great sickness. —Literally, And thou thyself shalt be in great diseases through diseasing of thy bowels. (Compare for the two synonyms: Deuteronomy 28:59, Proverbs 18:14)

Fall out. — Come out.

Day by day. —Literally, days upon days, i.e., probably, “a year upon a year,” or “in two years.” (Compare 2 Chronicles 21:19 and 1 Samuel 1:3; Isaiah 29:1.)