Bosses on the show called a medic to tend to Chris, and he was advised to pull out of his appearance - which would have inevitably made him miss out on his position in the upcoming finale.
The 34 year old didn't listen to the doctor, and was even sick just seconds before he went onstage - but he made it through his performance nonetheless.
"The doctor ruled out food poisoning - it might be the winter vomiting bug. He was in a really bad way."
He tells The Sun he's had a lot more interest from women since appearing on the series, but due to staying at London's swanky five-star Corinthia Hotel he feels it would be inappropriate to take advantage of the situation.
He adds: "I'm not exactly Brad Pitt - but 'The X Factor' has got me a few birds. But it's not a good look for the hotel if I was bringing loads of them back. It's not respectful.
"I would have preferred if they'd got us a Premier Inn and then my room would be full every night."
However, the musician is adamant his womanising is not affecting his ambition to win the show.
He adds: "It's stressful being on 'The X Factor' but I'm not neglecting my practice or anything. You just need a break."