sounds like the same thing I have.  It starts as a small red hard bump near the joint on my fingers on my right hand.  The sore/joint gets swollen and slightly red.  Sometimes it gets so large it almost makes my finger look crooked.  My hand gets swollen and stiff.  This hangs around for a couple weeks and then goes away.

I went to the doc for it and he ran all the RA tests and they all came back negative.  Any ideas?