If anyone knows of links to articles about this problem, in particular pertaining to the playing of the wooden flute, please could they add them to this thread or pm me. I’d like to know a little bit about its possible causes and ways in which it may be addressed.
Check some of the bagpiper forums (forae?). There is a similar issue for some pipers called, “piper’s palsy.”
Really… 
Happens when the little finger of the right hand is unable to play a grace note called a birl. A sort of short “trill” between low A and low G.
Piper Joe
I don’t know if you can post a video of your issue on this forum. But it might be helpful to see if there is something minor like the way you are holding the flute that is giving you a problem. If you’ve been a player for a while and the problem is new, it might be time to consult with an Occupational Therapist. They are like Physical Therapists but specialize in hands among other things.
A locking digit (one that refuses to bend or to straighten unless you force it, as with the other hand) sounds like trigger finger. Steroid injections to suppress inflammation or surgery to release the tendon sheath may fix the problem, but you need to speak with a hand specialist.
Thanks, I’ve been taking anti-inflammatory tablets and trying to play with a looser grip which seems to be helping. What was happening was that my little finger seemed to be swollen and was affecting the e finger’s mobility. I think I may need to practice less for a while and improve my posture.
If it were me I would tape the pinky at the joint that locks. Some support might help. If it doesn’t work, nothing lost.