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I'd suggest you take activated B12 separately, in high dose, for 3 months and get retested. This would be methylcobalamin 1mg if your test was around 400pg/ml. If your results were lower than that, you would do better to take 5mg methylcobalamin daily....on an empty stomach...no food for 1 hr after.

Ranges in US still go down to 200 or so and that is pretty low.
If you tested near 400 then that is just borderline.

Watch your sugar and carb intake too, as that can begin pre-diabetic nerve damage.

You can buy methylcobalamin now at Walgreen's and Costco. Or online at Amazon.com or iherb.com or Puritan's pride. It is not expensive and often is the first thing to fix when people get nerve problems.

Get your vit D checked too, because fixing that will improve things if low and supplemented.

B12 and Vit D are often low in American adults today.
Are you taking a statin for cholesterol? CoQ-10 is often given for that, as well as CPK testing levels.