What’s wrong with Janet Jackson? The 42-year-old singer was transported to the Royal Victoria Hospital in Montreal on Monday, as she “got suddenly ill” during a sound check, just a few minutes before her show was due to start, according to a statement released by W&W Public Relations.

Rebecca Burns, a spokeswoman for the hospital where the star received medical treatment, explained that Janet Jackson was released only a couple of hours after being admitted. However, Rebecca Burns gave no further information upon the singer’s condition or her mysterious illness.

Janet Jackson is currently on a North American tour to promote her most recent album, “Discipline.” Nevertheless, she canceled her Montreal concert scheduled for Monday night, which would have been the star’s first appearance in the city in seven years, due to her undisclosed health problems.

In addition to this, the artist’s next shows, which were programmed to take place in Boston and Philadelphia on Wednesday and Thursday, respectively, have also been postponed and no information was given on when they will be held.

These aren’t the first gigs the King of Pop’s sister cancels. Last Friday, Janet Jackson suspended the Detroit concert of her “Rock Witchu Tour,” citing “production constraints.”

An unnamed source told PEOPLE that the singer had frequently stated that she was suffering from exhaustion. “A 42-year-old body can’t handle what a 22-year-old body can. I can tell you that she’s definitely tired. It was probably exhaustion. She is doing back-to-back, three-hour shows, and her body isn’t the same as it used to be,” the source informed the magazine.

Back in April, she canceled an appearance on “Saturday Night Live,” citing another illness. Jermaine Dupri, the singer’s boyfriend, told MTV News at the time that the star had been “really sick.”

Which leaves us wondering: What is Janet Jackson suffering from? I sure hope we find out soon.

In the meantime, Janet Jackson is expected to resume her tour on Saturday in Greensboro, N.C.