Index finger injury: collateral ligament?

Hi all.  While warming up at the gym, I felt a slight pain on the insdie of the first knuckle of my index finger.  I could climb fine without pain and no stiffness afterward so kind of forgot about it. About a week later, while doing nothing, it started to hurt again but continously and proceeded to get stiff and hard to move.  I was able to get a quick appointment with an ortho clinic, who didn’t see any obvious evidence of an injury in the x ray but said an MRI.  I’ve rested it and much of the pain has gone away but it’s still slow to bend and makes a crunchy sound when I do.  It’s not a pulley injury (which I’ve had before) and feels like what would be the equivalent of an MCL injury in your knee (which I’ve also had).  Anyone ever experienced this, and what was your outcome?