Where are the words in my mind coming from, I have never seen a Mistress of pain in my life and I have a low pain threshold, so I have to ask myself what is it all about?
You are certainly not the first person to wonder this! The Greeks chalked it up to the Muses, goddesses who inspired the creative ideas of all artists, be it poetry, music, painting, sculpture, what have you. And a lot of the artists I know these days still are not able to explain creativity any better than that. When a writer or musician friend of mine is suddenly stuck and can't create, I hear the phrase "My muse has left me." quite often.

I used to wonder where my creativity came from (I also am a writer), but now I don't worry about it so much. It doesn't matter to me. I just enjoy watching the story unfold and the surprise roads it can take me down. I get to learn a lot about myself; I say often "Wow, I didn't know that turns me on!" or "I had no idea I thought so much about ___."

I guess for some people, where a thought came from or why you are having a thought matters a lot. To me, that's not important; what's important is what I do with the thought once I have it.