your fasting sugar is way to high. Ideally your blood sugar should be less than 140 all the time and even better if it less than 120. 500 metformin is a low dose, so it could still be increased. You may also focus on low carb eating and exercise / weight management.
You need to talk to your Dr about increasing your metformin or taking additional medications (increasing metformin, adding other oral meds or using low dose insulin).
If you are not able to reduce your blood sugar the burning pains (diabetic neuropathy) will likely progress and get worse. You are also at risk for other diabetic complications.
Yes, B12 may help for a short while, but most important is getting your blood sugars under control.