Madonna has cancelled three dates of her Madame X tour dates in Boston, saying she was experiencing "overwhelming" pain.
"Please forgive this unexpected turn of events," she told fans on Facebook.
"Doing my show every night brings me so much joy and to cancel is a kind of punishment... But the pain I'm in right now is overwhelming, and I must rest and follow doctor's orders."
The star did not specify the cause of her injury.
However, earlier this month, she told fans in San Francisco she was suffering from a "torn ligament" and "a bad knee".
Madonna is notoriously reluctant to cancel shows, abandoning only a handful of dates over the course of her 37-year career.
When she was inducted to the Rock And Roll Hall Of Fame in 2008, Justin Timberlake even recalled how the star had given him vitamin B12 injections to stop him succumbing to illness while she was working with him.
"She gave me a shot in my ass and looks at me and says, 'Nice top shelf,'" he said "That was one of the greatest days of my life."
However, the Boston shows are not the first setback on Madonna's Madame X Tour.
She postponed the opening dates in New York in September due to production delays. Then, after several dates at the BAM Howard Gilman Opera House in New York, she had to call off a show due to injury. The opening night of her LA residency was also cancelled.
Tour promoter Live Nation said the scrapped shows will not be rescheduled "due to the tight scheduling through the balance of the year". Refunds will be automatically issued to credit card holders.
The Madame X tour, which sees Madonna trading sports arenas for intimate theatre venues, is due to come to the UK in January 2020, with a 15-night residency in the London Palladium.