Left wrist pain at top of backswing and after follow through?

I get occasional left wrist pain also, though not nearly as severe as you describe. I think what causes it is not maintaining a flat left wrist at the top of my back swing and starting the swing with a bent left wrist or worse, maintaining it to some degree through the swing. This is just what I find when I'm at the range and my left wrist starts getting sore.

You may be flipping the club at the bottom and if you come up thin with your shot it could cause pain.

Nope I've never had it before my swing changes. Well the recent ones that I have been making were I'm trying to change my grip a little bit to make it more neutral other than so strong as it was, but the main thing I am working on now is my backswing, and my takeaway. Where I have been noticing some pain is at the top of the back swing the outside part of my wrist would hurt really bad, but that should be because shouldn't the wrist hinge or cock naturally when going back? And when i've tried to get a more flat wrist going back it would still hurt, even a little more. My last swing change is that I've been getting out of a shanking fit, so I am trying to come more around and rotate more on my downswing and get my hands more inside. I've been working on those swing changes, but the pain in the left wrist is persistent most on my follow-through,when I'm finishing my swing. It feels like an abrupt stop at the top that also can strain the muscles in my forearm, which I've noticed on occasions