Elton John has cancelled a series of Las Vegas concerts after doctors urged him to rest.
The singer went to hospital in Los Angeles for a series of tests but went home the same day.
He told website TMZ that it felt “strange” not to be able to perform the concerts, but promised he would be back.
He said: “All I can say to the fans is: ’sorry I can’t be with you’.”
He is due to play at the British Queen’s Diamond Jubilee Concert, organised by Gary Barlow, alongside acts including Tom Jones, Ed Sheeran, JLS and Jessie J.
The show takes place in front of Buckingham Palace on June 4.
The singer recently announced he had signed a book deal to publish “the very personal story” of how AIDS affected his life.
The book, which will be called 'Love Is The Cure: Ending The Global Aids Epidemic', will include his memories of friends including Queen frontman Freddie Mercury, who died of an AIDS-related illness in 1991.
The star and his civil partner, David Furnish, became parents of a son, named Zachary, via a surrogate mother in 2010.