There's a code in NASCAR: Whatever the injury, no matter how painful, a driver will never get out of his car.
Auto racing is a tough-guy sport, where even the admission of an injury can be seen as weakness. Drivers will race with severe illnesses, torn knee ligaments, broken bones and, in Dale Earnhardt Jr.'s case, concussions.
"In order for me to get out of a race car, I would probably have to be incapacitated," driver Regan Smith said earlier this year. "I would probably crash on the racetrack because of whatever was ailing me before I would get out of my car."
And that can be a problem – as it was for Earnhardt Jr.
When Earnhardt Jr. blew a tire during an August 29 tire test at Kansas Speedway, he hit the wall with an incredible 40 g impact. He knew right away something was wrong, but with the Chase just weeks away, Earnhardt Jr. told everyone he felt fine.
"You know your body and you know how your mind works, and I knew something was just not quite right," Earnhardt Jr. told reporters at Charlotte Motor Speedway on Thursday. "But I decided to just try to push through and work through it. I'd had concussions before and knew exactly kind of what I was dealing with."
Emergency personnel at the track evaluated the driver in an ambulance and cleared him to fly home. That night, he flew to a Washington Redskins preseason game. For all anyone knew, Earnhardt Jr. was OK to race.
He wasn't, though. He hid his injury and said he was only "80 to 90 percent" by the time the Chase began two weeks later. Earnhardt Jr. was feeling completely back to normal by Talladega, but then the Big One happened on the final lap.
In that wreck, Earnhardt Jr. sustained a more minor 20 g hit – and it was only on the rear of his car. The impact spun him around rapidly, though, and he knew immediately he'd suffered a setback.
"The car spun around really quick and just sort of disoriented me, and I knew that I had sort of regressed," he said.
Reporters gathered at his car after the race could see Earnhardt Jr. was in pain, holding his head before conducting an interview. But he insisted he felt fine and privately hoped the symptoms would clear up in a couple days.
When his headaches persisted on Tuesday, though, he consulted neurologist Dr. Jerry Petty.
Earnhardt Jr. was cleared by a neurological exam, and an ensuing MRI checked out normal. But upon going through Earnhardt Jr.'s concussion history with the driver, Petty decided he could not clear the NASCAR's biggest star to race in the next two events (Charlotte and Kansas).
Petty will wait until Earnhardt Jr. is headache-free for four or five days, then give him a stress test to try and induce a headache. If the symptoms don't return, Earnhardt Jr. will get in the car for a test lap or two.
"If that goes well, we'll probably clear him to race," Petty said.
NASCAR vice president Steve O'Donnell said Earnhardt Jr. showed "guts" in admitting he wasn't feeling well. But the truth is, Earnhardt Jr. only came forward after he realized he wasn't fully healed from the first concussion.
Just two days after the tire test crash, Earnhardt Jr. was on track for practice and qualifying at Atlanta. He finished seventh in the race, by he wasn't all there by his own admission.
"When you have a concussion, the symptoms can be really mild, and then they'll typically go away after a couple days and you feel perfectly normal," he said. "But then when you get in a car and you go around the track at a high rate of speed, you start to understand that some things just aren't quite where they need to be and some reactions just aren't as sharp.
"You really can't get a measurement of that until you're in the car. There's just no way of knowing until you can drive."
In Earnhardt Jr.'s case, he realized he wasn't all there but "wasn't willing" to tell anyone because of the impact it could have on his season. Would he lose his shot at a championship in the midst of his best and most consistent season ever?
"With the Chase coming up...if I was to volunteer myself to medical attention and be removed from the car, I didn't know how difficult it would be to get back in," he said.
Earnhardt Jr. chose to seek out a doctor's advice after the Talladega wreck rattled him. But for parts of six weeks, he was on the track at 200 mph while his brain wasn't at full health.
"I think you saw the process work in terms of Dale Jr. knowing he had an issue," O'Donnell said.
But did it?
"Concussions are mostly self-policed, and only you know how bad they are," Brad Keselowski said. "Whatever amount he had (after Kansas) wasn't enough to feel like it was a detriment to others, whereas this time, it is."