Is this a late-onset allergy to metal?

My thumb has been really dry, irritated, and raw for several weeks. I’m trying to figure out what it is, since it’s only my left thumb. I saw that the base of my right ring finger now has similar symptoms. It makes sense that the one ring I wear caused this, since I play with the ring with my left thumb.

I’ve been wearing the ring since March. Why is it only doing this now? Could it be related to the changing seasons?