'The X Factor's Louisa Johnson was diagnosed with a wheat intolerance at Judges' Houses.

Louisa Johnson at Judges' Houses

Louisa Johnson at Judges' Houses

The 17-year-old hopeful performed for mentor Rita Ora and her advisor Meghan Trainor in Hollywood for the next stage of the competition but is terrified she won't be selected for the Live Shows because she wasn't feeling her best on the day.

Louisa said: "Unfortunately I had a bit of a tough time. I woke up on the morning of my performance with an awful headache that got worse as the day went on. They called a doctor who diagnosed me with a wheat intolerance, which can cause headaches.

"I wasn't able to perform to the best of my ability. Chloe [Paige] has it, too, so she's been giving me lots of advice on how to deal with it since getting back to the UK."

Meanwhile, despite being in Rita's Girls category, Louisa has revealed she's been getting a lot of support from the Overs' mentor Simon Cowell and the Groups' Cheryl Fernandez-Versini.

She told OK! magazine: "I feel like he [Simon] really wants me to succeed, it's like he's my 'X Factor' dad. Cheryl has been lovely, too. After my audition she walked past me and said, 'I'm going to fight for you'. It made me really happy."

Louisa Johnson is telling you she wants to stay | The 6 Chair Challenge | The X Factor UK 2015