Dale Earnhardt Jr. knew immediately something was wrong during a 2012 crash at Talladega, where his car was hit hard from behind.

He was asked on his radio if he was OK, and it was clear Earnhardt was not.

"I don't know. I mean, I don't know how many of them hits like that I can take," NASCAR's most popular driver told his crew.

Dale Earnhardt Jr. is helping the Sports Medicine Concussion Program at the University of Pittsburgh Medical Center raise concussion awareness. Jerry Markland/Getty Images

He recounts the crash in his personal story of his own battle with a concussion in a video made for the Sports Medicine Concussion Program at the University of Pittsburgh Medical Center. UPMC on Wednesday launched the website ReThinkConcussions.com to detail treatments.

Featured on the site are Earnhardt and baseball catcher David Ross, who were both treated at UPMC by Dr. Micky Collins, the clinical and executive director of the Concussion Program. Collins is considered one of the leading experts in athlete concussions.

Earnhardt's issues began in late August 2012 when he crashed during a test at Kansas. He knew something was wrong with his head, but continued to drive for the next several weeks. The accident at Talladega led to a second concussion -- one he couldn't ignore.

"As soon as I got out of the car, I was like, 'Something is wrong with my head again,'" Earnhardt says in the video. "I was really moody, very angry, I couldn't go anywhere where people were. I was very scared."

He was forced out of his car for two races and sought treatment from Collins at UPMC. Earnhardt's situation also led NASCAR to require baseline concussion tests for all drivers this season. Drivers were urged to get an ImPACT test before the 2013 season as NASCAR worked to implement the rule on baseline testing.

A 30-second version of Earnhardt's video will air nationally during the upcoming NASCAR races at Martinsville and Homestead. It will also be shown regionally during the World Series and evening news broadcasts.

Ross' video details how he suffered a concussion when he was struck in the helmet with a foul ball in 2013. Later that same day, at his son's birthday party, he said he felt "foggy and seasick" and his wife noted he wasn't engaged and had an empty look in his eyes.

Ross said he took a few days off, but his performance was off when he returned to the playing field.

"If you don't know what a concussion is and what you're looking for, you are just going to keep trying to trick yourself," Ross said.

It came to a head when he was cut off by another driver in traffic and was unable to control his temper. Scared of his behavior, Ross's wife said she'd tell doctors if he did not. It led him to treatment at UPMC. His video will be aired regionally.

Other pro athletes who will be featured in the ReThinkConcussions.com initiative include quarterback Brady Quinn, second baseman Brian Roberts and Tyler Hansbrough of the NBA.

"An important reality is this: concussion is treatable if managed properly," said Collins. "That should be the conversation now instead of the near-hysteria. People should think of concussions as a treatable injury in the right hands, not some untreatable condition that causes you to retreat to a dark room."