The young singer, who struggled during the first day of Boot Camp, complains to producers that he doesn't feel well and that he may "pass out".
"I feel so dizzy and weak," he reveals. "I'm so scared I'm going to pass out.
"I just feel so weak."
Jahmene is comforted backstage by Nicole Scherzinger and Louis Walsh, who tell the performer that they still "believe in him".
"I need you to remember why you're here and why you love to sing," says Scherzinger, who hugs the youngster.
"We can't wait to hear you, no matter what you do, all we can ask is that you just sing your heart out, that's all you can do."
When he takes to the stage, Jahmene performs 'Will You Still Love Me Tomorrow'.
Afterwards, Gary Barlow expresses doubts about whether the teenager is ready for the big stage.
"This show is tough love, it is. Because I tell you what, these contestants, they're on Twitter, they're being written about in the papers, it's really hard. If this is what he's like at this point I would worry," the Take That star tells the other judges.
24 acts will be voted through to the Judges' Houses stage of the competition on tonight's show, which airs at 7.30pm on ITV1.
Photo Gallery - X Factor Boot Camp Day 2
Copyright: THAMES TV/SYCO