Kyle Busch’s death certificate, obtained by multiple outlets, reveals that the two-time NASCAR champion silently fought a severe lung infection for weeks. Kyle Busch, the two-time NASCAR Cup Series champion who died May 21 at age 41had been battling bacterial pneumonia for “days to weeks” before his death, according to his death certificate. The document, obtained by multiple media outlets on Wednesday, paints a grim picture of his final hours. Busch’s pneumonia progressed into sepsis roughly one day before he died, and the sepsis then triggered a cascade of additional organ failure. The sepsis led to disseminated intravascular coagulation —…