was back onstage on Friday, January 15, just hours after illness forced her to cancel a concert, and wowed fans on 's TV talk show. The singer was due to perform at Purdue University in Indiana on Thursday night, January 14, but pulled out at the last minute after paramedics discovered she had an irregular heartbeat.
She later logged onto to Twitter to apologize to fans, writing, "I've been crying for hours, I feel like I let my fans down 2nite. An hour before the show, I was feeling dizzy and having trouble breathing. Paramedics came to take care of me, and told me my heart-rate was irregular - a result of exhaustion and dehydration. I can't apologize enough for how sorry I am. I could hear my fans cheering from my dressing room, I begged everyone to let me go onstage."