An entirely unscientific survey

I am left-handed. Recently, due to a temporary desk set-up, I've been mousing right-handed at work. My shoulder is *aching* from extending over to the right and I think I've pulled something in my back. I note that, when mousing left-handed, the mouse is right there next to the keyboard; I hardly have to move my arm at all to use it. But you right-handed people - the mouse (if you have the usual type of keyboard) is further off center because it has to be on the other side of the arrow keys and the numberpad. If your body is centered so that your hands rest naturally on the home-row, your right arm is constantly reaching away to mouse, whereas left-handed mousers comfortably mouse and type with minimal shoulder joint extension.

I've been in a job where I'm at the keyboard constantly, all day, for over ten years, plus I'm on the computer at night. I have never had even a twinge of an RSI. In just a few days mousing right-handed, I'm experiencing horrible back pain and my arm is sore.

Is there any evidence anywhere that any of you know of that RSI occurs more often, per capita, in right-handed mousers than in left? Are there keyboards where the number pad and the arrows are on the left, so that the right-handed mouser isn't put in this position?

Also? Ow.