[SpaceGorilla]

If it were me in your situation, I might spend some time off the keyboard (days, weeks, whatever it took) doing light ergonomic finger/grip training and plenty of stretches. You can accompany this with fist clenches to keep blood flowing and to keep your mobility up. Getting the right nutrition (and sleep thanks maple) is also something super important that we tend to ignore more than we should. It can basically cripple you until you get what your body needs. Multivitamins can make some of that much easier if you choose to go that route.
This whole problem might have something to do with your setup on the keyboard, too (imagine using a really weird setup like zc bm with your hands all scrunched up), so don't rule that out entirely. I personally find it more ergonomic to go with a non linear setup like wd ko, and what works for you might not be the same as what works for the rest of us.