Cyrus was placed on medical rest by her doctors last night and was forced to console her fans via Twitter.
The concert was in Kansas City, Mo., not the state of Kansas, though given Cyrus' health, the mix-up was quite understandable. She spent the rest of the night on Twitter, complaining about hospital television, quoting the Flaming Lips and assuring her fans she'd rather be onstage performing than cooped up in a hospital.
There is no word on whether or not the shows will be rescheduled, though Kansas City guests have been assured their tickets will be refunded at the point of purchase.
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It has been a tumultuous month for the 21-year-old pop star, following a tour bus fire en route to her concert in New Orleans on March 17. She canceled another show on April 7 in Charlotte, N.C., citing a bout of the flu.
The next scheduled stop on the Bangerz Tour after St. Louis is set for Nashville's Bridgestone Arena on Friday, April 18. Cyrus' complete tour itinerary is here.