I noticed that when i produce a full swing (racket elbow drops down and approaches the shuttle first then followed by arm extension), when i practice the swing at home, at the point of contact (with pronation), my elbow is fully extended and the sudden cocking of my wrist actually puts pressure on my elbow joint (as it approaches 180 degrees) and it pushes my elbow joint in.. I dunno if this is a problem cos when i practice at home my stroke stops after my pronation and i do not follow through (cos i have limited space st home) but then in real games i do follow through. This doesn't really happen with my limited swing cos during point of contact with pronation, my elbow is only bent at around 170 degrees...
I have your same problem! I find when I am playing my teachers, in other words going all out, I hit the birdie as hard as I can and find my elbow hurting afterwards. Especially on my backhand. Im not the kind of player that will hit over my head just to avoid the backhand, I use it often and my elbow hurts after.
Elbow joint Check out this introduction article on Elbow-joint: http://www.articleworld.org/Elbow-joint