I don't know if I've had a nerve "sprout" versus "re-growth" or some other mechanism.

All I can tell you is that while my nerves were "re-growing" I had a sensation that felt like tiny vibrations happening inside my foot, almost like a microscopic worm was burrowing in there. This itself was not horribly painful. What was painful was the pins and needles and burning sensation that accompanied. That lasted for many months.

To be honest my neurologist was unable to differentiate between nerves regrowing and nerves dying. The pain is very similar, the only way I could tell is that my nerve function improved over time in a quantifiable way. For instance, when the nerves were dying I couldn't feel a tuning fork vibrating on the ends of my foot. A year later I could.