"It was crazy. It was insane," David tells ET. "I'm sitting there in the Kodak Theatre [with the] judges to my right, my group's there ready to go and my voice slips away."
More than 26 million people watched as Donny and Marie's nephew was sent home.
David continues, "By lunch, I started to have a vocal problem. I didn't know what it was. I wasn't sick or anything. By dinner, I couldn't sing a note. I couldn't get a tone out, and I had full-blown laryngitis within about eight hours."
That isn't David's only illness. He also suffers from something that put him in a wheelchair just last year.
"Doctors determined that I was bit by a mosquito and that in turn triggered Multiple Sclerosis," he shares. "My dad [Alan Osmond] has had MS for 21 years and he's been a huge role model for me."
Because of David's age, this is the last year he is eligible to compete on "American Idol," but not to worry. ET is going to give him his big break, so tune back in tomorrow when David will be performing on the ET stage!
Visit the website below and click on the photo to see an expanded interview with more than was shown in E.T. on Thursday night. be sure to listen to David sing from the Entertainment Tonight studios on Friday.