Two exits, no waiting.

I'm hoping that anyone has an idea of what's going on with my mom.  For at least five years, she has been having episodes that she refers to as "Two exits, no waiting".  She will have severe vomiting and diarrhea simultaneously.  She'll be in the bathroom for hours.  She says that it happens after over-indulgence, and not just a specific food.  It could be any kind of food - healthy or not-so-healthy.  

She's had her gallbladder out and for a little while that seemed to help.  After a few months her episodes of 2E came back, much to our disappointment.  Could this be a malabsorption issue?  We have no clue and it's so painful and draining for her.  Any thoughts would be greatly appreciated!!