ET was backstage at Monday night's "Dancing With The Stars," where dancing pro Derek Hough tells ET about sister Julianne Hough 's health update, and the celeb dancers talk about next week's competition! "She's getting better," Derek says about Julianne's recovery from surgery. "The first couple of days after surgery were a nightmare. She was in a lot of pain, but she's a fighter. She's up and about." Julianne's partner Cody Linley also tells ET ...