Mary Lou Retton gives update on her health: 'They still don't know what's wrong with me'

Seven months after she was hospitalized with a serious illness, Olympic gymnastics legend Mary Lou Retton said her doctors "still don't know" exactly what illness continues to affect her lungs. 

Retton, 56, told "Entertainment Tonight" that she still needs to breathe from oxygen tubes in her nose every day as she continues her recovery. 

“They still don’t know what’s wrong with me,” she said. “They’re calling it a rare form of pneumonia.” 

The retired gymnast spent about a...