Re: Internal Pain
The Chinese have a saying "grinding out sand" and I've been told that this refers to the process of getting through the "blocks" or "stoppages" that have been accumulated in the body over time.
What it often feels like to me is the "undoing" of old injuries. So there may be discomfort, I'm careful to avoid injuries while training, that area gets cleared up and then another problem is revealed. Repeat.
While I don't think this process develops 'teh internalz" by itself, my experience has been that it is a consequence of proper internal and structural training. Like a complimentary sort of thing.