Jeremiah has gone through terrible suffering because of God’s judgments. At first, he had to proclaim God’s judgments with great terror and sadness (see Jeremiah 4:19; Jeremiah 15:17). Then he experienced God’s judgments himself, when the city fell. Jeremiah describes his life as one of darkness.
God often lets the innocent suffer together with the guilty when he brings his judgment (“the rod of his wrath”). Think of Jonathan who died with Saul, and Daniel and his friends who were taken along in exile. Jeremiah shows his own brokenness at God’s actions in a remarkable way. In this song, he at first cannot bring himself to mention God by name. He will only speak of “he” and “his,” until verse 18.
1 I am the man who has seen affliction under the rod of his wrath;