Focus on keeping your movements short and tight, rather then trying to mimic speed. I still try to do things fast, and I always end up sounding terrible, and hurting myself. Just remember that the shorter your finger moves, the less time it will take to hit the note, thus focus on less movement over faster movement.
One thing that I find is helping me is that I try to keep stretching my fingers every chance I get. The muscles can build up tension over time and stretching helps to make sure they don't strain an injury, it will also help the muscles to react faster (hint: there is no substitute for the technique mentioned above, but faster is faster).
If your finding that your finger hurts every time you use it, you may already have injured it. I'm not sure what the best way to heal it would be, but not using it sounds like a pretty good idea.
