I get the same sensation, but stronger during a flare. Normally, by adjusting the water temp, it's not so extreme.

Maybe try and switch to soaking in a warm tub with Epsom salts? I find the magnesium in the salt and warm water really helps with muscle pain and relaxation in the evening. Also if you can control your spray on the shower head you could try to switch it to more of a rain shower (gentle spray) so its not so forceful.

I get this everytime I shower. If you can maybe turn down the shower pressure that does help, and try adjusting the temperature, too, sometimes that can play a factor. That aside, a new shower head may do the trick; if you can find a rain head, those tend to be much more gentle than standard shower sprayers and don't pummel you so badly.

I just had my first experience with this... Pins and needles all over my body I had to quit and get out and I still feel the pins and needles. Not a very good feeling.

Yep. The spray actually hurts when it hits you.