Rihanna cancels another show in her Diamonds World Tour just hours before it was supposed to begin.

The 25-year-old was supposed to perform in Dallas Tuesday night but was forced to cancel, citing an unspecified "illness."

A statement from Live Nation, the tour's promoter, was issued on the night of the concert, in response to angry fans who have purchased tickets and hotel rooms just to see the star perform. The statement read, "Update: Unfortunately, Rihanna is unable to perform this evening in Dallas due to illness. Please hold tickets pending a rescheduled show."

The undisclosed "illness" has led to speculations of Rihanna carrying Chris Brown's baby as she was reportedly photographed going to a doctor's office.

According to gossip website TMZ who's had a close encounter with the R&B singer, "Rihanna came out of a medical building in Bev Hills Tuesday ... and said she's doing a lot better, but it's done nothing to stop the pregnancy talk...Thing is ... it's been more than a month now and there are clearly still issues. Because the info coming from Rihanna's camp has been sketchy ... there have been a slew of tabloid stories speculating that she's pregnant."

Unfortunately, the public is not so convinced with her "illness" anymore, after cancelling four times since the start of her tour and two in a row this week. To ignite the pregnancy rumors even more, Riri admitted in a recent interview in the magazine Elle UK that she could see herself having a kid with Breezy five years from now. Her exact words were, "I will probably have a kid... I want to be healthy and happy."

However, there is another angle to the real reason why she's been cancelling her shows, saying the Barbadian singer is experiencing drug overdose.

Rumors began after her tour buses and trucks were stopped twice at the Canada-Winnipeg border, and inspectors have found one of the passengers in possession of marijuana.

Meanwhile, amid the concert cancellations, fans expressed their disappointment, attacking Rihanna via social media and sending her hate mails.

An upset Dallas fan tweeted, "Her priority is drinking, smoking, drugs, instagram & chris."

A source from an entertainment website also revealed, "Go check out Wiz Khalifa's Facebook page. Rihanna and him smoking a blunt. Nice to know why she cancels her concerts. Stop giving this woman money, she doesn't even like her fans."

As of now, it is still unclear if Rihanna is going to cancel any more shows this week.