These are names of cities and towns. Dimon was the principal city of the country of Moab. Several modern versions have "Dibon" instead of "Dimon." (See: [[rc://en/ta/man/translate/translate-names]])
Here "I" refers to Yahweh. Also, "Dimon" refers to the people who live there. Alternate translation: "but I will cause even more trouble for the people of Dimon" (See: [[rc://en/ta/man/translate/figs-metonymy]])