A couple months ago, I had a sharp, shooting pain in my left hand. It was right after I switched from an Apple keyboard to using a WASD mechanical keyboard.
After a couple weeks of pain, I realized I'd been reaching my left hand to the Escape key in Vim, probably hundreds of times per day! No wonder my hand was hurting.
I finally resolved to remapping Vim not to use the Esc key, in favor of using
the consecutive letters
jk in its place. Lo and behold, my pain went away.
Hopefully it resolves yours, too!
To remap your Esc key like I have, add the following line to your
inoremap jk <esc>