In reply to Ed Brighteldman:
Hi Ed,
I've had the exact same experience on my middle and ring fingers pulling on a 2 finger pocket - it sort of creaked rather than popped but definitely audible. I'd provisionally identified as a flexor unit strain.
Mine has lasted since late March so far.
Dave McLeod's advice on his Online Climbing Coach blog is to treat the same as a pulley injury.
In short: rest until no longer causing pain through normal range of motion, regular icing, climb on it again after 2-3 weeks avoiding grip positions that aggravate it.
Obviously usual caveats apply regarding listening to stuff on the internet and going to see a doctor.
Regarding recovery/climbing, after a week or so I was able to climb again without pain. I find it only twinges in very open grips and pockets, so I'm sort of cupping as much as poss and avoiding pockets.