Well, your D is very very low. When it gets this low, you cannot absorb calcium well, and then the muscles get strange and you can have paresthesias. If this is not fixed your body will rob your bones and eventually you will get osteoporosis.

You should be on OTC D3 at 1000IU for every 10 pts you need to increase. For you to get to the new lowest "normal" of 50, you'd need 4,000IU daily. If you are heavy or large you may need a bit more. Do this for 3 months, and then get retested to see how your level has changed and how you feel.

The B12 is just above the lowest normal...for people with neuro symptoms, it is suggested to take B12 anyway (Dr. Snow suggests this in his medical paper), since it is non-toxic. We here like to keep our B12 at 1000 or more for best results.

Axons are the long parts of nerves that travel distances to the spine. They enervate muscles mostly but some pain signals also. When damaged by inflammation or autoimmune attack, or toxins, they may repair if B12, folate, B6 and Omega-3s are present to rebuild the myelin. Some drugs block remyelination, like statins for cholesterol. So it might be that reinervation is similar. Length dependent PN is a damage to the axons.

Let's see what Glenn thinks.
Since you are showing axonal damage, you might consider Acetyl Carnitine, as a supplement. Start at 500mg a day (divide doses 250mg twice a day) and work up by 500mg a week to 2 grams. Do this for a month or two and see if there is any improvement.

Methylcobalamin B12 1000mcg or 5000mcg a day on an empty stomach, to bring you up a little. 5000 would be faster, and can be lowered to 1000 later if you choose.

Fish oil 3 a day with food. Or 2 reg. Krill oil a day with food.
Multivitamin for the rest (without iron if you are male or postmenopausal female).

Vit D3 4,000 IU daily.

See what happens or changes.