"I've been hiding a show injury and chronic pain for some time now," Gaga said in a series of tweets. "Over the past month it has worsened. I've been praying it would heal... I hid it from my staff, I didn't want to disappoint my amazing fans. However after last night's performance I could not walk and still can't."
Because of the severity of Gaga's synovitis, a severe inflammation of the joints, her doctor has asked her to postpone her upcoming shows. "To the fans in Chicago, Detroit & Hamilton, I hope you can forgive me, as it is nearly impossible for me to forgive myself. I'm devastated & sad."
Beyond Hamilton, there are 14 more cities on the Born This Way tour, which is scheduled to finish in Tulsa, Okla., on March 20.