I think, Sarah, you are misinterpreting the terms.

Certainly you have A neuropathy... but there are over 100 causes of neuropathies. Things that act globally in the body, like diabetes, or toxins, or autoimmune, GBS, or deficiencies attack many sites not just one.
Your EMG showed large fiber involvement. But the EMG cannot tell anyone WHAT is causing that.

You came here initially saying you had a neuropathy from your bariatric surgery. You said you were not absorbing your vitamins etc. Then you said they were tested as "normal". So I have lost track of your situation and am getting confused, including the later information about your back and arthritis at your young age.

Mayo is not perfect. Many have come here from Mayo, and found it less helpful than anticipated.

I certainly do hope your issues clear up, and your pain starts to recede. Sometimes people do get better.

At your age doctors are hesitant to offer opiates. There are other pain management techniques, including SCS devices and pain pumps.
Here is our forum on that subject:
http://neurotalk.psychcentral.com/forum118.html

Asking doctors, as Joan has pointed out, about "stronger" drugs, is sometimes met with them closing down, and making assumptions about your motives. This happens with many many patients. Many neurologists have the personality of a "rock", and are not very compassionate about how you feel and suffer. We've had many discussions about that subject here!