A post shared by Selena Gomez (@selenagomez) on

We had no idea!

Selena Gomez told the world that she secretly underwent a kidney transplant this summer on Instagram, and her friend Francia Raisa was her donor. The "Bad Liar" singer's organs had been failing as she battled lupus, and it got so bad at one point, she was hospitalized after boyfriend The Weeknd's concert in Chicago back in May, TMZ reports.

"I’m very aware some of my fans had noticed I was laying low for part of the summer and questioning why I wasn’t promoting my new music, which I was extremely proud of. So I found out I needed to get a kidney transplant due to my Lupus and was recovering. It was what I needed to do for my overall health," she wrote.

"I honestly look forward to sharing with you, soon my journey through these past several months as I have always wanted to do with you. Until then I want to publicly thank my family and incredible team of doctors for everything they have done for me prior to and post-surgery," she continued.

"And finally, there aren’t words to describe how I can possibly thank my beautiful friend Francia Raisa. She gave me the ultimate gift and sacrifice by donating her kidney to me. I am incredibly blessed. I love you so much sis. Lupus continues to be very misunderstood but progress is being made," she concluded.

We're so glad she's OK!