Then I dissociated. Not just a little 'drifting off' either, but a complete disappearance. I'm not sure how long I was 'out', but I came back when she was finishing the massage and being more gentle again.
She's been my massage therapist for a long time, so afterwards I was able to tell her that I had dissociated, and we talked a bit about what had happened just beforehand, so that I would know in future how to spot it. Since getting home I have been thinking of talking with her about setting up a 'safe word', like in BDSM, if I can't say stop, but I can say something. I'm sure she'd be open to that. I completely trust her, and it's not surprising that a massage, especially a painful one, could trigger something like this off, but I'm pissed off that the bastard is still affecting me in this way.