Justin Bieber The Show Must Go On

3/9/2013 4:40 AM PST
0309_justin_beiber_infJustin Bieber bounced back from his brief hospital stay to perform again last night at London's 02 Arena ... and was spotted after the show getting mobbed by fans on his way back to his hotel. 

Bieber -- who collapsed backstage during his show on Thursday -- complained on Twitter yesterday of still being winded ... but performed as scheduled without incident.