I think that nerve is too raw for a tens. A tens is used on a complete nerve....your nerve is not attached at the distal end.

I would look into nerve regeneration technology....I know in Israel there was a clinic that regrew spinal nerves, and actually got spinal cord injured people walking, perhaps there is something like that available for major nerves being severed.

I would think some of what you are going thru is what an amputee feels, but your part is still there. All that nerve senses is that it is no longer connected to the hand, and as far as it is concerned the hand is gone. If and until it restablishes contact with the hand, my thought is, that it will signal pain, as in an amputee, basically phantom pain, but with you, you have the limb.

Does any of this make sense?