your pains have nothing to do with your sensitivity. It's most likely due to an existing condition or the way you play and position your arm/wrist/fingers. you may be putting too much pressure on certain parts of your wrist or holding your mouse in a strange way.
ive never had even a touch of uncomfortability let alone pain playing thousands of hours of this game with high and low sensitivities. I palm grip my mouse.
use a mouse that's relative to the size of hand you have. sit in a position that seems natural for your body and limbs. sit at a height that allows you to have comfortable control of your mouse with arm movements while minimizing wrist and finger movements. make sure no parts of your arm or wrist are under any pressure, edges of desks and thick mousepads are common pressure points that may lead to carpal tunnel.
fingertip and claw grips are notorious for causing wrist and finger pain. there's a bunch of csgo players whose careers might be about to go up in smoke because of pain and inflammation. most csgo players use a fingertip hybrid grip.
this strawpoll is really shocking to me. never would have guessed so many people have pain when they play this game. follow my advice above and maybe it will help you. personally if I had pain while playing and didn't know what was causing it I wouldn't continue playing. this game isn't really worth potentially damaging one of your most important body parts permanently.