I'd never heard of gout in a finger, but your case sounds like that of an elderly lady (90's) in whom gout was diagnosed. Research gout. Google: gout in finger, cause, remedy
Check out every lead, no matter how remote. Check into complementary medicine here at MedHelp. Real all the threads in this forum, any related ones, here, and at other websites of alternative solutions. If it is gout, you will probably be able to avoid surgery by diet and supplements. Good luck. Hope this helps. Let us know what it turns out to be.
It could be arthritis, especially if there is a family history of it. Have you consulted with your primary doctor or rheumatologist? That would be my advice.