Now in London promoting her newest single "Come and Get It," Selena Gomez suddenly cancelled a live twitter chat with fans.

Gomez cited a mysterious illness, and fans flocked to twitter, speculating about whether Selena Gomez was feeling under the weather, lonely without her boyfriend Justin Bieber, or perhaps pregnant with a baby, since she did not identify the reason why she felt "horrible."

On Wednesday morning, Selena Gomez wrote on her twitter account, saying "Sorry to everyone for having to cancel today.  I am not sure if I am sick or ate some bad food but, I feel horrible.  I am going to take the rest of the day and try and get better for tomorrow. So Sorry :( Love you guys."

Polydor Records also tweeted, confirming the cancellation and apologizing, "We are sorry to announce that due to illness Selena is unable to take part in a @VEVO_UK twitter chat today. Sorry we're gutted too."

Since Selena Gomez did not express specific details of why she was not feeling well, her twitter message left fans jokingly that she may be pregnant with Justin Bieber's baby.

Twitter user @GreysonsKeys wrote, "Oh my Gosh.... Selena Gomez is Pregnant!! LOL lmao xoxo."

On the other hand, some fans wondered if she was just feeling lonely and blue now that she is physically separated from her boyfriend, Justin Bieber. Other fans simply wished her good health and asked her to feel better.

Having just recently reunited with Justin Bieber, Selena Gomez and her relationship with the big star have been closely monitored by the public. Just a few days ago, the two's backstage kiss at the 2013 Billboard Music Awards on May 19 and the disgusted reaction by Selena Gomez's close friend, Taylor Swift, garnered much attention.

On September 8, Selena Gomez will be stopping by London again for her 2013 Stars Dance World Tour.