HI there,
It sounds like there is an inflammatory component to this problem. Check if there are aches and pains in other joints or refer back to GP to screen for arthritic conditions. In the mean time, treat the swelling aggressively - contrast baths 2-3 x/day), support with coban (a stretchy, compressive tape good for fingers),perhaps ultrasound subaqueously and gentle range of movement exercises. Strengthen in pain free range. Hope this helps.