Pop star Lily Allen has published a picture of a sick note from her doctor online to explain the cancellation of four European festival performances.
"I've got sinusitis and strep throat," the singer wrote on her MySpace page. "I don't even know what that is."
The 22-year-old, whose hits include LDN and Smile, says she has been advised to take a couple of weeks off.
Allen reassured fans she would be fit for her appearance at the V Festival in the UK later this month.
"I've have literally been around the whole world in two weeks," wrote the singer, "from London to Japan around Australia and then to LA and Vegas then back to LA for a 17-hour video shoot.
"Now I'm back in London eating my mum's chicken soup cause I'm afraid the travelling has caught up with me."
"Before anyone starts trying to accuse me of neglecting my fans I want to apologise and say how sorry I am, but I can't risk causing any permanent damage."
Earlier this year, Allen postponed a string of dates in the US saying she was "bored" and wanted to concentrate on her second album.
Since then, she has had her US work visa cancelled in connection with her arrest in London in June.
The arrest arose from an incident outside a London nightclub in March and resulted in a caution for common assault.
The star, who is nominated in the best newcomer category at the MTV Video Music Awards, said she would do "everything I can" to honour the US tour dates.