Ask HN: Pain in thumb when using MacBook Pro's touchpad

I have started to feel pain in the muscle at the base of my right thumb. This is due to using the built-in touchpad of my MacBook Pro.

I have no problem with my left hand, so I believe the keyboard is not the problem.

Does anyone else experience that? Most of the material I can find talk about wrist pain, but that's not my issue.

I've been trying to make changes to my posture. I've realized that I was keeping constantly my right thumb in a slightly elevated manner, maybe to avoid having it touch the touchpad. I've tried to correct that by forcing myself to let my right thumb rest on the touchpad, but this feels very unnatural, and I feel it actually also puts strain on my thumb.

How do you guys position your right thumb? Is it resting on the touchpad or the frame of the mac?