The B12 [ methylcobalamin ] is certainly a good idea, sounds like your B12 levels must have been low then, sorry to harp on about diabetes but it is the most common cause of nerve damage and a good one to rule out and often looked over if levels aren't really high but in a prediabetic range which can cause the exact same damage as a full blown diabetic.
I was told by a GP I had no sign of diabetes going by an overnight fasting glucose test, he said it was completely normal at 4.6 or [82.9] in your numbers, but when i got to see a neuro he said the overnight fasting glucose test is not something he would go by to rule out diabetes at any level and ordered the glucose tolerance test which showed I had prediabetes.