LONDON (AP) - It's been a rough week for Justin Bieber: Getting booed for being late, struggling to breathe mid-performance and fainting backstage, then caught on camera clashing with paparazzi.

But the 19-year-old pop sensation appeared to have recovered Friday for his final concert in London, singing and dancing to thousands of adoring fans at the O2 Arena.

Earlier Friday, the star made headlines when he got into an altercation with insult-hurling paparazzi, lashing out at a photographer with a stream of expletives as he was restrained by minders.

"Ahhhhh! Rough morning. Trying to feel better for this show tonight but let the paps get the best of me," the singer posted on Twitter soon after the altercation with the photographer, which took place as he got into a car earlier Friday. The scuffle was captured on video by Channel 5 News and widely broadcast by Britain's media.

"Sometimes when people r shoving cameras in your face all day and yelling the worst thing possible at u...well I'm human. Rough week," he wrote on the social networking site.

The clash came just hours after Bieber said he was "getting better" following breathing problems he suffered during the previous night's concert. The star took a short break to go backstage, where he was given oxygen, and had to be briefly hospitalized for a check-up.

A spokesman for the O2 Arena said Bieber was treated backstage during Thursday's concert after becoming short of breath, but recovered and finished his set.

"He was treated by our team of medics and after further examination they didn't find anything more serious or worrying."

A spokeswoman for Bieber said he was feeling "a little under the weather." She demanded anonymity to discuss the star's condition.

Bieber later posted a shirtless photo of himself in a hospital bed, saying he was getting better and listening to Janis Joplin. Before that on Twitter he thanked "everyone pulling me thru tonight."

Video footage from the concert shows Bieber appearing to fade during a performance of his up-tempo hit, "Beauty and a Beat." He slows down, puts a hand to his head then bends over, resting his hands on knees before walking slowly to the back of the stage.

Bieber's manager, Scooter Braun, appeared onstage and told the crowd that the singer was feeling "very low of breath" but would come back to finish the show.