Robert Irwin shed more light on his Dancing With the Stars injury during the season 34 finale on Tuesday, November 25. Following a visit from Derek Hough for the judges' choice round, Irwin, 21, grimaced in footage from his rehearsal with pro Witney Carson taken Saturday, November 22. "I've been dealing with rib pain because the intercostal muscles of the ribs are under a lot of tension. It's been getting worse progressively," he explained to the camera. Carson, 32, admitted she was "extremely worried" about Irwin's safety in their dances.