Sharp Chest Pains

First off I don't know what to put this under, anyway.  I know this girl that has been having sharp chest pains she has had them most of her life, but recently they have been getting worse.  The pains seem to start in middle of her chest then radiate around to her back.  Sometimes though, they may not start in the middle but on one side like earlier tonight she said it started on the left side of her chest.  They usually hit a couple of times before it goes away, and recently they have gotten so bad she can't breathe and she mostly always collapses.  When the pain is gone there is still a lingering dull ache.  She has been to a specialist about this and he didn't know what it could be he ran an EKG, and had her on a heart monitor and he still didn't know.  Does anybody have any idea as to what it could be?  I know I probably haven't described it as best as I can, but please any information would be helpful.  Thanks.