HOT-headed Rob Kardashian got himself into trouble with the law – and now sources say his protective mom Kris Jenner is desperately trying to keep her only son out of jail!

The problem began on March 27 when the 26-year-old “Keeping Up With the Kardashi­ans” star took his shirt off in a West Hollywood gym parking garage after a workout session with celebri­ty trainer Gunnar Peterson. Rob, who recently packed on 40 pounds, blew up after a female photographer snapped a “money shot” of his tubby physique.

According to a compalint filed  by the photog, Rob was so irate he stole her camera’s memory card and smacked her in the face. Rob was handcuffed and briefly taken into custody, says the source. After ques­tioning, he was released without any charges being filed, but the Beverly Hills Police Department is currently investigating a potential felony rob­bery charge, which is punishable by up to nine years in prison. Now Kar­dashian momager Kris has stepped in to track down the woman in a fran­tic attempt to make sure Rob stays out of the slammer.

“Kris is calling all of her contacts and anybody else that might know who this woman is,” said a source. “She’s desperate to find this pho­tographer so she can pay her off to get Rob out of trouble, and she’s throwing around HUGE dollar figures to make it happen.”

So far, Kris han't had any luck luck, says the source.

“No one wants to help her because everyone knows that Rob has a hor­rible temper, and a lot of them feel he needs to finally face some con­sequences,” added the source.

“He can’t keep run­ning to his mom for help every time he gets in trouble. And they both need to learn that money can’t buy everything.”