NASCAR driver Kyle Busch experienced shortness of breath, felt he was overheating and was coughing up blood the day before his death, according to a 911 call obtained by The Associated Press.Busch died Friday morning (AEST) at age 41 No cause of death has been given, though his family said earlier he had been hospitalised with a "severe illness" three days before he was to compete in the Coca-Cola 600 at Charlotte Motor Speedway.Busch was testing in the Chevrolet racing simulator in Concord the day before his death when he became unresponsive and was transported to a hospital in Charlotte, several people familiar with the situation told the AP.The people spoke on condition of anonymity because details have not been disclosed by Busch's team or family.During the emergency call placed late that afternoon from the General Motors training facility, an unidentified caller calmly told the dispatch: "I've got an individual that's (got) shortness of breath, very hot, thinks he's going to pass out, and is producing a little bit of blood, coughing up some blood."Busch was lying on the bathroom floor inside the complex and the caller told dispatch "he is awake," according to audio provided by the Cabarrus County Sheriff's Office.The man then gave directions on where emergency responders should go and asked that they turn off any sirens upon arrival.NASCAR CEO Steve O'Donnell addressed reporters at a news conference on Saturday morning but declined to answer any questions about the cause of death or any health problems that might have plagued Busch."We are 24 hours from getting a phone call and out of respect for the family, and they have asked for privacy, I am not going to address anything," O'Donnell said. "But transparency is something that we all believe in