Some 10 years ago my B-12 value was a low of 96, coinciding with the onset of my peripheral neuropathy. B-12 injections brought the value up to 300+ and I've since switched to oral B-12 pills and the value has stabilized at 400-500. Whether the B-12 was a cause or effect of the PN is not known. My PN has continued with foot drop the most serious problem. I'd say, take the B-12.
B12 is important for the production of red blood cells, healthy vascular and nerve functioning, etc.
Did he/she also tell you about what foods you can also eat that are high in B12?
You do not want your B12 levels to be low for long; can cause problems.