This is a common problem in people who play computer games, especially those that are mouse heavy. The solution is pretty simple actually.

Simply lower your mouse sensitivity. Now you use your mouse by moving your entire arm instead of your wrist.

Watch how this guy uses his mouse: https://www.youtube.com/watch?v=X89152oocsA

Of course they do it to aim better, but it also puts less strain on your wrist and hand