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Rihanna fans had right for concern last night when the pop star tweeted a photo of her arm hooked up to an IV.

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Rihanna released the picture as a reply to one of her followers who asked why she hadn't been active on the site Tuesday, as she is an avid Twitter user.

This comes after Rihanna's stunning appearance at the "Oscars of fashion," New York's Met Gala.

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A source tells ET that the singer "had a fever and flu since last week and needed an IV but is fine now." Rihanna's Twitter feed corroborates with this statement, as she tweeted a photo of herself about to board a private jet from New York to Los Angeles early this morning.

"My ride home," she wrote. "NY days LA nights."