CONCORD, N.C. — Dale Earnhardt Jr. knew he had sustained a concussion in an August crash that was so jolting, other drivers commented about the accident on Twitter immediately after the impact.
Earnhardt didn't see a doctor. He was too worried he would be yanked from his car, derailing his long-unfilled Sprint Cup championship hopes.
He kept the injury a secret until a 25-car accident on the last lap in Sunday's race at Talladega gave him a lingering headache.
NASCAR's most popular driver sought attention from a neurosurgeon, who found Earnhardt had indeed sustained two concussions in six weeks and could not be medically cleared to race. Earnhardt said Thursday he will sit out the next two races, a move that ends his championship chances.
"I would love to race this weekend, and I feel perfectly normal and feel like I could compete if I were allowed to compete," Earnhardt said. "But I think that the basis of this whole deal is that I've had two concussions in the last (six) weeks, and you can't layer concussions."
"It's incredibly sad any time you have to have something like this happen, especially with how hard Dale has worked to get into the Chase," driver Mark Martin said.
Earnhardt's first concussion came in an Aug. 29 wreck during a tire test at Kansas. He crashed into the wall when his right front tire failed. Earnhardt was seen in the back of an ambulance, but he was not treated in the infield care center and did not seek further examination elsewhere.
He said Thursday he knew he sustained a concussion. "You know your body, and you know how your mind works, and I knew something was just not quite right," he said. "But I decided to just try to push through and work through it."
He didn't give himself the same leeway after the accident at Talladega. Though Earnhardt said the impact was half as hard as the Kansas hit, "I knew as soon as it happened that I had reinjured myself."
biffle on pole: Greg Biffle won the pole for Saturday's Bank of America 500 at Charlotte Motor Speedway. Regan Smith, who will drive Earnhardt's No. 88 Chevrolet, qualified 26th.