We learned on Dancing with the Stars tonight that Derek Hough is INJURED. He has hurt/inflamed the bulge in his vertebrae and neck and will quit DWTS temporarily. Mark Ballas will take over and be Shawn’s new partner since Shawn advanced tonight.

Derek said yesteday, “I’ve had [the bulge] for a couple years..but once it flares up — like it did today — it sort of immobilizes me.” Shawn added, “I saw him today turn his head and I was like, Uh-oh..I was like, What did you do? It slowly got worse.”

We will keep you posted on Derek’s injury and health and will let you know when he will return to DWTS.

UPDATE: After the elimination show, Derek headed to the doctors. We’re told he will take the week off to rest. But he will still “be there to choreograph and kinda oversee,” Shawn says, adding, “Mark will be doing the movement. And then, depending on the injury, depending on how he feels, it’s up in the air as to whether he’ll be on the show Monday or not.”

Shawn told E!:  “If anybody were to step in, it’d be Mark. I love Mark and I love Derek. I cheated on Mark the first time, now I’m cheating on Derek. It’s kind of a weird triangle going on.”