The Bank of America 500 weekend at Charlotte Motor Speedway opened with breaking news Thursday morning when Dale Earnhardt Jr. announced he will not drive in Saturday’s NASCAR Sprint Cup race. Regan Smith will replace Earnhardt in the No. 88 AMP Energy / National Guard Chevrolet as NASCAR’s most popular driver recovers from multiple concussions.

Earnhardt suffered a concussion last weekend at Talladega in a spectacular 25-car pileup. He admitted Thursday that injury came on top of a previously unreported concussion he received Aug. 29 during a tire test at Kansas.

“[After Kansas] I knew something was just not quite right but I decided to push through it; I’ve had a concussion before, and I knew kind of what was dealing with,” Earnhardt said. “I felt pretty good for a week or two, at least 80 or 90 percent. By the time I got to Talladega I was 100 percent. It was an odd kind of hit; the car spun around real quick and it disoriented me. I knew as soon as it happened that I had reinjured myself, for lack of a better way to describe it. I knew I had kind of regressed. It was not even half of the impact I had at Kansas, but it was enough to cause me some concern.”

Earnhardt said that although he knew he had “reinjured” himself last Sunday at Talladega, he waited a few days before getting checked out to see if the symptoms would clear. When his headaches persisted, Earnhardt said he first called his sister, Kelley Earnhardt Miller, and then Dr. Jerry Petty – a neurosurgeon who serves on the International Council on Motorsports and acts as neurosurgeon for the Carolina Panthers.

Dr. Petty said he first performed an impact test and then an MRI on Earnhardt, and both tests came back normal, indicating there was no permanent damage. However, based on the recent concussion at Kansas and the persistence of headaches, Dr. Petty said he couldn’t in good conscience clear Earnhardt to race this weekend.

Earnhardt, who was 11th in the Chase for the Sprint Cup, will also miss next weekend’s race at Kansas and will be eliminated from championship contention.

“I admire [Earnhardt]. I think a lot of guys would try to play hurt,” team owner Rick Hendrick said. “But when the doctor tells you if you get hit again right away, it could be catastrophic ... We’ve got a lot of years left to race. I always want to be on the side of safety. I applaud Dale for raising his hand and going in to get checked out.”

Earnhardt said he had no plans to be at the track this weekend, expecting that his presence would be an unnecessary distraction.

Dr. Petty said Earnhardt would need four to five days without headaches and perhaps an on-track test before being cleared to drive.

“I would love to race this weekend, and I feel perfectly normal and feel like I could compete if I were allowed to,” Earnhardt said. “But the basis of this whole deal is I’ve had two concussions in the last four to five weeks, and you can’t layer concussions. It’s very dangerous.