So, I am not sure, but I might have given myself a similar injury to yours today.
I loaded a pocket at an odd angle at the works, and my ring finger made two very distinct crunching sounds.
There appears to be pain and mild swelling around the joint, more so then the pully positions currently.
Strangely the pain is when I straiten the finger.
Have you gotten any further in figuring out exactly what your injury is?
Everyone seems to talk about a pop, but mine was definitely a crunch, so not sure of diagnosis.
My game plan is the Dave Macleod thing from yester-year; rest and slow recovery with plenty of stretching/ice.
Will avoid NSAIDS, on the basis that the swelling provides a function, and I don't want to inhibit that.