The Wrecking Ball hitmaker was admitted to a Missouri hospital in April after suffering a bad reaction to medication she had been taking for a sinus infection.Although she was discharged last week, she was forced to postpone the remaining portion of her North American Bangerz tour in order to recuperate.Cyrus was due to take to the stage in Amsterdam on Friday but was forced to postpone that date, as well as her concert in Antwerp, Belgium on Sunday. Both gigs have been moved to June.On Wednesday, the 21-year-old's condition was updated via a statement on her website which reads: "After a period of improvement, Cyrus' symptoms have returned and doctors will not permit her to travel. This type of extreme reaction can last up to 27 days and Cyrus must remain under doctor's care at this time."Cyrus herself took to her Twitter page to express her frustration with the situation, writing: "R u (sic) f**king kidding me?!?!?!?? #aprilcangof**kitself"The singer still plans to go ahead with her concert on 6 May in London's O2 Arena, and is also sceduled to perform at Belfast's Odyssey Arena on 19 May.