Lady Gaga has postponed four of her upcoming shows on her North American Born This Way Ball tour. She broke the news on Twitter to fans in Chicago, Detroit and Hamilton, Ontario on Tuesday, explaining that her doctor has ordered to her to postpone the dates. She had two shows planned at Chicago's United Center for Wednesday and Thursday. The Mother Monster explained that she's been suffering from a case of synovitis, or severe inflammation of the joints. She admitted that she has been "hiding" the "chronic pain" while onstage for the past month, but it has worsened. She even confessed to keeping her illness away from her staff, but after her Monday show in Montreal has been unable to walk. Gaga was deeply apologetic to the fans, saying that "it is nearly impossible" for her to forgive herself for letting them down. She said she was hoping to heal as soon as possible, but did not offer details on when the four cancelled dates would be rescheduled.