Justin Bieber -- I Got a Tummy Ache From Food Poisoning

Justin Bieber must have eaten some bad empanadas in Argentina ... 'cause the singer just revealed he's got food poisoning.

Biebs dropped the crappy news on Twitter Sunday evening, but quickly assured fans his sour gut would not result in any canceled concerts ... at all.

It's one more piece of bummer news for Justin whose current Central and South American tour has been plagued with issues -- like destructive fans, fake hookers, graffiti tickets and hotel problems.

Good thing Pepto-Bismol is global.