Two questions:- You mentioned lactic acid buildup in your post, do you ever experience this when playing in addition to the wrist pain?- Did the pain go away when you took a break?
- Yep, I experience the burning/ fatigued feeling from lactic acid buildup as well as wrist pain quite often- although I understand this is normal (?), especially when playing fast passages or octaves and things like that- it fades after I finish playing said passage.