Depending on if the herniated disc is rubbing against a motor nerve or not (which it seems it is - hence why he was limping as he injured his back) you can play through it if the pain is manageable. Romo is a tough SOB but sounds like it was too much even for him, and he probably wouldn't have been able to protect himself from further injury limping around like that.
Also, it doesn't matter who the Cowboys have as a DC when they are on their 19th defensive linemen (literally, not a joke), missing the best coverage linebacker in the game, and playing rookies at safety and nickle and dime coverage. Kiffin should still retire, but he doesn't have healthy NFL caliber players outside of Scandrick and Church. Ware and Hatcher are both playing through nerve and back issues and are shells of their selves from earlier in the year. They lost Anthony Spencer, Ratliff, and Tyrone Crawford after the draft but before the season - the whole season started off fucked on defense.
Also, it doesn't matter who the Cowboys have as a DC when they are on their 19th defensive linemen (literally, not a joke), missing the best coverage linebacker in the game, and playing rookies at safety and nickle and dime coverage. Kiffin should still retire, but he doesn't have healthy NFL caliber players outside of Scandrick and Church. Ware and Hatcher are both playing through nerve and back issues and are shells of their selves from earlier in the year. They lost Anthony Spencer, Ratliff, and Tyrone Crawford after the draft but before the season - the whole season started off fucked on defense.