*Usher has postponed two more concert dates on his European tour after a doctor prescribed bed rest to fight off a respiratory illness.

The singer already pushed back a planned gig at the O2 World in Berlin, Germany on Wednesday after falling ill earlier this week. He returned to the stage for the rescheduled concert on Thursday, but had to cut the gig short after just a handful of songs.

Usher lip-synched his first two numbers and danced poorly to them, according to local tabloid B.Z. Fans on the edge of the stage reportedly started complaining. Boos were also heard. In response, he reportedly lowered his head and stood silently on the stage for about four minutes before leaving altogether. The stage lights came on and fans were told the star was too sick to continue the show.

He subsequently postponed tonight’s show in Rotterdam, Holland and now he’s pulled two more upcoming performances – Saturday’s (Jan. 15) gig in Oberhausen, Germany and Sunday’s (Jan. 16) date in Antwerp, Belgium in a bid to regain his health.

Usher’s rep tells WENN, “Usher is suffering from an upper respiratory illness which is currently preventing him from performing a proper show. After consultation with doctors, he has been advised to reschedule the upcoming dates in order to get the rest he needs to ensure a complete recovery.”

The Rotterdam show has been pushed back until March 1, while the Antwerp gig will now take place on March 7. Rescheduled dates for the halted Berlin concert and the Oberhausen show have not yet been confirmed.

“I have been very excited about my European Tour and I deeply regret having to reschedule the shows,” said Usher in a statement. “I am truly sorry for any inconvenience I have caused my fans. My fans are the best in the world and I am looking forward to getting better so that I can give them the show they deserve.”