The pain in your finger may be due to a condition called RSI(Repetitive Strain Injury). I heard there could be many reasons for you to have an RSI. In this case you already mentioned that this finger is used mostly in typing.
I had an RSI months back on my right pinky finger due to typing. I did some stretching exercises found on the internet which you could gather easily on the web. I also changed my typing habits a bit in such a way that i don't have to use the right little finger, which may not be practical at all cases. The point here was to give some rest for the finger. Now like the above comments, no one could diagnose you over the internet so i recommend you to go and see a doctor!