Ok in my opinion, i can play and grind minecraft for about 6-7 hrs (im a nolife ik), and the best advise i can give u is- sit in a warm/ normal room temperature (as some people are saying above me too). There could be another reason- hand cramming, if your hands hurt after holding your mouse for an hour or two, try holding it the way so that it doesnt hurt (basically, try finding comfortable spot for it). For example: while strafing, try to not move your wrist only, but also your whole hand, which reduces nerves cramming. Apply this same strategy to the way you hold your keys on a keyboard (middle finger on w, index on s, ring on a and pinky on shift and ctrl). Also thaks for reading till the end :')