Kelly Clarkson hosted the 2019 Billboard Music Awards on Wednesday night (May 1), for the second year in a row, and although fans couldn't tell, the singer was in some serious pain. Clarkson was suffering from appendicitis and had her appendix removed shortly after the big show.

Clarkson revealed the news of her surgery on Twitter on Thursday (May 2), in response to a fan praising her "flawless" hosting job. According to Clarkson, though, what viewers didn't see is her "[breaking] down in tears after the show from pain."

"BUT thanks 2 all the amazing people @ Cedars-Sinai I flew home directly after the event, nailed the surgery early this morning, & feeling awesome now!" Clarkson adds. "Bye bye appendix."

Clarkson's 2019 Billboard Music Awards hosting duties included a performance of her new song "Broken and Beautiful," from the UglyDolls movie, as well as an opening medley of some of the year's biggest hits. Songs by Florida Georgia LineMaren MorrisDan + Shay and more were in the mix.

Dan + Shay were onstage, too, during the all-genre awards show, performing their hit "Speechless" with pop singer Tori Kelly. Also at the 2019 Billboard Music Awards were Florida Georgia Line and Kane Brown. Both country artists were nominated at the show -- FGL took home Top Country Song -- and were selected as presenters as well.

2019 Billboard Music Awards: See Pics From the Big Night