Dale Earnhardt Jr. found himself in the midst of a 25-car pileup Sunday. (Dale Davis / AP)

Dale Earnhardt Jr. sustained a concussion in the 25-mile pileup Sunday at Talladega Superspeedway and will miss the next two Sprint Cup races.

Earnhardt’s condition was diagnosed Wednesday afternoon, Hendrick Motorsports said in a statement, and he seemed dazed immediately after the crash, which occurred on the last lap. Because he was able to drive away from the wreck, he was not required to undergo an examination at the time. Regan Smith will drive Earnhardt’s No. 88 Chevrolet.

In a press conference in Charlotte, Earnhardt indicated that he was more seriously injured than he’d believed in a hard crash into a wall in late August at Kansas Speedway. He was evaluated at the time and released. However, the wreck Sunday aggravated his condition.

Although he initially called the pack-racing style at restrictor-plate tracks that often leads to multi-car pileups ”bloodthirsty,” he tempered his comments Tuesday.

“I regret making a bit of a scene and not considering the fact we’re going to be in a totally different race car for 2013. … It was a bit heat of the moment, and I kind of regret getting that emotional about it,” he told SB Nation. “But I was just really upset about how that all went down. We’d run so good. I was really, really happy with my car in that race and I thought we should have been able to finish really good.”

Earnhardt’s consecutive starts streak will end at 461 and he is almost certain to finish last in the 12-driver Chase race.