This is a very interesting take!

I myself tend to think that Turin did this to himself, rather than Glaurung, because he could not bear the memory of Beleg's loss and his involvement in it, even after he had made his song about it.

But I can see how you arrived at your conclusions! And it could be both factors, I suppose, together with Morgoth's curse?

And that parallel you draw with the flash of lightning is certainly very striking!