Perhaps Justin Bieber has been wearing a gas mask because he really can't handle the air in London.

His bad week in the UK got even worse when he was rushed to the hospital after a concert last night. Justin informed the crowd mid-show that he wasn't feeling well and went backstage to get checked out, where he "collapsed," according to TMZ.

Justin's manager Scooter Braun told the crowd that the singer had been feeling "very low of breath" throughout the show.

Despite recommendations from doctors to cancel the remainder of the show, he soldiered on 10 minutes later and finished the gig. Concertgoers were cheering and chanting his name in support throughout the final few songs.

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"He got oxygen from emergency personnel. He insisted on finishing the show. He is on the way to the hospital right now," said his rep to E! News.

But even in the ER, Justin doesn't seem to be much of a fan of clothing. He tweeted yet another shirtless, undie-showing pic from his hospital bed and told fans that he will be just fine. (Seriously, does he own pants?) "Getting better. thanks for everyone pulling me thru tonight. best fans in the world. figuring out what happened. thanks for the love," he wrote on Twitter.

The good news for his London fans is that tonight's show is still expected to go on as scheduled. Of course, this isn't the first time that Biebs has had medical drama on-stage. He threw up during the opening night of his tour last October and had a similar vomming moment back in 2011.

Do you think Justin should be performing tonight?

Photos courtesy of Getty Images and twitter.com/justinbieber