The Emmerdale actor is performing as a lion tamer in Sunday's (March 11) circus-themed special, but has been struggling to keep the prop under control.
"Matthew loved getting into character as a lion tamer and really cracking the whip," an insider told The Sun. "But the whip's quite long and he accidentally caught himself between the legs.
"It would have been all right if it had just happened once, but after three times he was in serious pain. It's really knocked his confidence and he's very embarrassed."
Wolfenden has since addressed the reports on Twitter, telling one fan who asked him if he was still having trouble: "Just a bit! It's got a life of its own!!"
The 31-year-old previously suffered a back injury and caused concern by dropping his partner Nina Ulanova while competing in Dancing on Ice.
Other more serious accidents to have occurred during the show include Jennifer Ellison stabbing herself in the head with a skate and Jorgie Porter slashing the face of her partner Matt Evers.