Found this, only skimmed it but think i found the important stuff:

The injury occurred against Oregon on Halloween in 2009. By all accounts, it was a routine hit, but after staying on the turf for a few seconds, he was removed from the game. Within days, he found himself in the hospital, where a specialist told him he had a "mild" case of spinal stenosis, a narrowing of the spinal column. "I've seen this over and over again," Jones remembers the doctor saying. "If you play the game long enough, things like this will happen."

The doctor told Jones he would be fine and he could play again. But the Trojans' team doctors thought the injury was much more serious and refused to clear him for contact; they eventually recommended that Jones retire from football. So the then-20-year-old spent his days wandering from class to the basketball gym to the weight room. "Just like a regular student," he says. Just a 6'3", 241-pound student who considered trying out for USC's basketball team.

"But in my head," Jones says, "I never let go of the fact that the first specialist told me I'd be okay."...

....At a loss, Jones began to wonder if other team doctors would clear him. So Carver High coach Dell McGee called Georgia, Florida State and Alabama on Jones' behalf. Not surprisingly, all of the coaches said that if doctors cleared him, they wanted him.

First, Jones received clearance from a doctor in North Carolina. Next, Georgia coach Mark Richt was by his side as he underwent tests at a hospital in Athens, three hours north of Columbus. "When Jarvis told me he missed drinking sweet tea," Richt says, "I knew we had a good chance." Once those Georgia doctors officially gave Jones their blessing, he sat with Richt at a nearby restaurant in June 2010. "Coach," Jones said, "I'm a Dawg."....

....As the 2013 draft approaches, Jones' neck will likely be evaluated once more. "There are no absolutes when it comes to stenosis," says ESPN injury analyst Stephania Bell, a board-certified orthopedic clinical specialist. "It's not uncommon for doctors to have differing opinions, and players must be evaluated on an individual basis. But if the condition is severe, injury could result in permanent neurological damage."

Jones insists that his neck is fine. No pain. No numbness. He says the injury's lone lingering effect is mental: "I know what it's like to not have this game in my life."