Welcome to our board.

First off I'd get the numbers you had when the B12 test was run.
What was the result? Interpretation of "normal" of this test is very spotty in US. If you are below 500... you need a supplement. You don't need shots as an only intervention.
Proper use of oral B12 can work as well. Do you take acid lowering drugs? If so you may be low in other things like folic acid, calcium, zinc, magnesium, iron.

Do you do cycle workouts? Ride a bicycle for exercise?
This may compress nerves.

Did you have thyroid testing?

I would investigate gluten intolerance. This can cause alot of neuro symptoms that do not show up on standard metabolic panels.
Here is an excellent resource:
http://jccglutenfree.googlepages.com/
This is our gluten board:
http://neurotalk.psychcentral.com/thread98657.html

Have you had fluoroquinolone antibiotics recently?
Do you take statins for cholesterol?
Have you been exposed to solvents/strippers?
Were you tested for heavy metal levels?
Did you receive a vaccine before this started?

The above questions reflect the possibility of mitochondrial damage. This would point to using acetyl carnitine and CoQ-10 to help in this area.

Check out the Quest diagnostic link that Glenn provided.
It has a more complete list of tests that are suggested for PN.

If you are alcohol intolerant, then that points to Thiamine as a support nutrient. The improved version of this is called benfotiamine and is used often for PN.