His ex-wife thinks it's football related. She says he's been suffering with depression since suffering a "brain injury" with the Bears. She thinks they'd still be married but for that injury. The death of a child is torturous for anyone, though. And the divorce was around the same time.
Here's an in-depth Chicago Tribune piece/interview on Kramer from 2012, months following his son's death.
I remember hearing about his son's death a couple years or so ago. No parent should have to outlive their child. Cant remember if that was the only one he had. Still brutal though.