A source tells TMZ that Justin Bieber has been acting out in an immature manner recentl;y because he's all messed up over Selena Gomez.

They broke up in December but Selena has been keeping contact which is messing with Bieber's head.

Read more here:

http://www.tmz.com/2013/04/03/justin-bieber-selena-gomez-breakup-acting-out-anger/

photo source:  961kiss.com