Quite possibly self-inflicted.
If you read Michelle Malkin, it's a virtual certainty. If you read the Daily Kos, to even suggest such a thing shows you are a horrible human being. I honestly don't know, but in the absence of any other evidence, I'll probably take the man at his word. I think something probably happened to him. What, when, how and where, well those are a bit more uncertain.
What amuses me is that some people are accusing him of being a media hound, while others are saying it's suspicious he won't talk to the media. And both sets probably agree the media are a bunch of lying hacks who will twist whatever he says to fit their agenda, so, surely, he'd be a damned fool to say anything to them.