As with any repetitive strain injury (RSI), rest, moist-heat-then-ice, massage, compression, NSAIDs and, of course, physical therapy can all help. For me, I've generally found that plenty of aerobic exercise to increase circulation through tight sore muscles is what will fix/relieve RSI issues the most quickly for me. YMMV. The main problem is that this is a long-term solution that can take months or years, not days, and healing will go a helluva lot faster if you simply stop the activity that's causing the pain or at least limit how much time you spend on it. But ignoring the pain and working through is liable to increase the injury and severity and frequency of pain. Geek hyperfocus and right-brain loss of time sense are not your friends, here. Slowing down might help, too.
Understand, also, that what hurts may not be pinpointing where the mechanical problem of muscle strain actually lies. You may have pain in your fingers, wrist, forearm, or elbow, but the actual mechanical problem could be in the shoulder, neck, or back. Pay attention to posture, and which muscles are actually in use, and concentrate on finding positions to relax them.
Ultimately, if this begins to bother you outside of the activity, or if you discern nerve damage, medical advice is the best way to go. Keyboard and trackball/pad RSI to the point of nerve damage meant I had to give up knitting altogether, since I still needed to be able to keyboard full time to earn a living. Healing was also, thus, incredibly slow, even wearing splits 24-7 for 9 months. Consider whether or not you can trade in some keyboard time for crochet time, or stay off keyboards outside of business hours. :)