Oklahoma quarterback Jackson Arnold was barking orders to the offense as it hurried to the line ahead of a key third-and-1 when the whistle was blown dead.When Arnold saw the OU medical personnel running out onto the field to attend to offensive lineman Jacob Sexton his shoulders slumped and his head titled back in disbelief. It was the second time Sexton needed help off the field on Saturday in Oxford, Mississippi.The Sooners’ offense was averaging 5.6 yards per play and in a 7-7 tie in the second quarter when Sexton when down with an apparent right leg injury.It was a crushing blow for an offense that’s been plagued by injuries all season and was finally showing life for the first time in over a month.Immediately after Sexton went down the first time, Ole Miss defensive end Princely Umanmielen faced little resistance coming off the edge to sack Arnold, resulting in third-and-long and a punt. When he went down the second time, the Sooners survived a scare when Taylor Tatum fumbled on a 13-yard gain, but J.J. Hester got a strip and recovery to get the ball back.On the very next play Umanmielen came off the edge again and blindsided Arnold, this time forcing a fumble the Sooners wouldn’t get back.Oklahoma was able to put together a touchdown drive before the half, but Sexton never returned and the Rebels would stifle the Sooners over final two quarters in a 26-14 loss.Venables didn’t offer any details on Sexton’s injury, but didn’t sound optimistic either.“He’s a little banged up, so, but he’s in decent spirit,” he said.The Sooners were already without five wide receivers, including Deion Burks. Geirean Hatchett has already been ruled out for the season and several others have been playing through injuries.The Rebels’ talented defensive line was held without a sack during the first quarter of the game, but had 10 over the final three quarters. That’s the most sacks ever allowed in a single game in program history, but only one more than the Sooners allowed against South Carolina last week.“We’ve gotta be better there. That’s terrible and we know that,” Venables said. “The first half was a little bit cleaner from that standpoint, we kept the quarterback upright and we had a nice rhythm and in the second half not so much.”The Sooners had 94 total yards in the second half after entering the break with a 14-10 ...