KELLY OSBOURNE suffered a seizure in front of a live studio audience while taping her show "Fashion Police" yesterday. Witnesses say Kelly turned to guest host MELISSA RIVERS and said, quote, "I don't feel good" . . . then fell out of her chair to the floor and started shaking. Melissa went down to the floor to help her . . . and an audience member who happened to be some kind of emergency responder jumped in as well. Fellow host JOAN RIVERS later said Kelly is "fine".