Thanks for the suggestions! I played a LOT with the Youtek SpeedPro (which is VERY stiff) and that's when the pain started to ramp up. I have recently switched to the Volkl C10 Pro which is very flexy, so we'll see if that helps.
I don't claim to be an expert at 4.0, but I don't think my technique is the problem, as the problem is fairly recent. We'll see if the Volkl flex fixes the issue.
4.0 | BLX Pro Staff 95 | Volkl Cylone Tour 17 @54lb