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.

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.

The star's Believe world tour is due to move on to Portugal on Monday, then continue across Europe, the Middle East, South Africa and North America until August.

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