Walking around wearing a gas mask, then showing up 2 hours late for a concert, being rude to fans, collapsing backstage last night...and now raging at a pap today in London! 

Supposedly, he fainted and needed to be treated with oxygen.  Eventually, he came back out, did four more songs, and went to the hospital.  To show everyone he was OK he tweeted a picture of himself in his underwear from the hospital bed... ummm, yea.

Click the pic to watch the video of the fight from TMZ...but be warned, it's loaded with the F-word!