UNLV football player Ben Christman experienced chest pains during practice the day before his tragic death ... this according to new docs obtained by TMZ Sports.
Las Vegas Metropolitan Police say an officer was dispatched to Christman's off-campus apartment shortly after 10 AM on Feb. 11 ... after receiving a 911 call from a teammate who found the offensive lineman lying on his back, foaming at the mouth and with purple fingers.
The caller and another player were administering CPR when the officer arrived .