Texas quarterback Sam Ehlinger in concussion protocol

Ehlinger sacked for 34-yard loss (0:41)

Sam Ehlinger is sacked by Trey Carter, who forces a fumble that is eventually recovered by Ehlinger for a 34-yard loss. (0:41)

Texas quarterback Sam Ehlinger is in the concussion protocol after sustaining a head injury during the Longhorns' 13-10 loss to Oklahoma State on Saturday.

The true freshman, who has started five of the Longhorns' seven games this season, missed practice on Sunday and is day-to-day, coach Tom Herman said Monday at his weekly news conference.

"I have no idea [when Ehlinger suffered the head injury]," Herman said Monday. "It was something that came up after the game and really after media stuff that he did postgame. That's when the medical guys kind of noticed something off and he was complaining a little bit. They evaluated him at that point, sent him home. Nothing concrete at that point Saturday night, gave him 24 hours.

"He came back Sunday and showed some symptoms."

Ehlinger did not show concussion-like symptoms after the Longhorns' 29-24 loss to Oklahoma on Oct. 14, Herman said. During that game, Ehlinger took a hard hit and was motionless on the ground briefly. Herman said following that game that the quarterback was evaluated for a concussion by team doctors after the hit but was cleared to return, which Ehlinger later did.

Ehlinger told reporters after the Oklahoma game that he was not confused at any point about where he was and that he immediately told team doctors he could return.

During the week leading up to Saturday's game against Oklahoma State, Ehlinger was "symptom-free," Herman said.

"My understanding is he was cleared, symptom-free, the entire week after the Oklahoma game," Herman said Monday. "Obviously he was cleared enough to go back in the game. And at some point, during the game against Oklahoma State, something happened."

If Ehlinger is unavailable, sophomore Shane Buechele will start on Saturday versus Baylor. Buechele started twice this season, the season-opening loss against Maryland and the Longhorns' 17-7 win at Iowa State. He won the starting job coming out of training camp and was the Longhorns' starting quarterback in 2016.

Starting center Zach Shackelford was also held out of practice Sunday while being evaluated for a head injury. Receiver Reggie Hemphill-Mapps was held out because of a sprained knee suffered versus Oklahoma State, but the team hopes to have him back at practice later this week.