Go to doctor ASAP. they can usually fix this issue when its starting out by opening up the pressure on the nerve canals, and if its just a infection they can prescribe something to that. However this has to be done before it becomes chronic. But again im no doctor. (they can usually also tell what ergonmic changes you need)
Most likely its the way you grip things and how you hold mouse. Laptop users seem to be much more prone to this than regular desktop users. Mainly because they dont reserve enough desktop space to the mouse. If you reserve a arms length of space for your hand on the table with the mouse you dont need to move the wrist at all. In fact when i teached computer use one on one about 30% of people use the mouse wrong (you use the mouse like you use a pen to draw long lines with movement of the elbow NOT wrist, wrist is more or less fixed, this alone doesnt fix the issue but cotributes to it) Anyway be sure your mouse has 3 buttons because the mouse wheel is the ergonomic killer number one. (using the wheel kind of move has very complex strains on your hand, if you use one it then should be VERY sensitive, and yes this attacks your wrist)
Anyway a trackball might help you out, unfortunately a trackball inst equal to a mouse in certain precision tasks and in certain cases the static nature of of your hand on one can actually be more of a strain then mouse. The alternative is to get a tablet agian it does not strain your wrist if you sue a pen properly however not all people manage to do that.
Basically once you break it its stays broken. Ive so far spent 10,000 euros on computer ergonomics alone (nothings broken yet, but see my friend has broken it and his bill is WAY over 10,000 somewhere closer to a hundred, remeber tough 10,000 is quite little money when spread out on 20 years). Because quite frankly trying to be cheap on this department is NON REPLACEABLE, even 20 somethings get inflicted.
So overview every single piece of ergonomically thing around your workstation, you will need a good desk, good chair a good monitor, and all of them must be placed right. You will also need to allocate for a good rest of the keyboard and whatever pointing device you go up with. Then check your eyesight and when you go to the optician tell him you want to chek your WORKSTATION sight and they will measure it differently. Quite often people need different glasses for workstation work than regular day to day work, youd be surprised how much this affects your overall ergonomics, since trying to see the screen is a subconscious function so just placing it right makes the body try to work mre correctly.
And one more thing, take the time to do other things than gripping the pointing device for prolonged periods. Yes worst case scenario is that you cant use computers as source of living. And no for havens sake dont eat painkillers for this.
PS: you can train to keep the wrist fixed too if you wish