Coach Mark Richt said after the game that he didn't have a definite diagnosis on Brown, who sat on the trainers' table with a towel over his head being consoled by teammates after the injury.
"I just know he hurt it pretty bad," Richt said. "I don't know if we've talked to his parents yet or not. It doesn't look like he'll be playing anytime soon."
Brown started the Bulldogs' first four games but struggled to find his rhythm all year. He had 51 carries for 181 yards and had averaged 3.5 yards per carry coming into the game.
He took back the starting job against the Commodores chiefly because Lumpkin blocked so poorly last week against Tennessee, and he had 11 carries for a season-high 75 yards at the time of his injury.
True freshman Asher Allen took over Brown's kickoff return duties.