I have looked extensively across the internet and can't find an answer to my bizarre situation. Almost every time I have a massage I orgasm. It seems to happen the most when they work on the lower part of my back. It is often unpredictable, occurring when I least expect it and am not even aroused. It doesn't matter when my masseusse is male or female either, it just happens.

They aren't necessarily intense orgasms, rather mini ones, but I've sometimes had up to 4 or 5 during a massage.
It has never happened with a friend or partner massaging me either, nothing even close. What is so peculiar about it is that I do not achieve orgasm easily when it comes to oral sex or masturbation. It is achievable, but I have never in my life orgasmed during intercourse and have often had even the most dedicated partners wanna give up trying. I myself put this down to medications, anatomical design and most likely having a few sex issues so am mentally unable to let go.
Can you tell me if i am alone in this? It bothers me in that I almost feel guilty getting a massage as if I was paying for sex, but I really enjoy my massages, orgasm excluded. Thanks for any advice you may be able to offer.