With your vastly distributed symptoms and investigations done, neuropathy should be the diagnostic consideration. Following investigations should be done by your primary care physician or a neurologist (I understand that many have been already done);
1) Electromyography/nerve conduction studies (EMG/NCS)
2) MRI of the spine and brain
3) blood glucose, glucose tolerance test and glycosylated hemoglobin
4) serum B12 level with methylmalonic acid (with or without homocysteine),
5) serum protein electrophoresis
6) Anti-nuclear antibody
7) Lyme testing
8) Rheumatoid factor
9) Sjogren's syndrome testing (Anti-Ro, Anti-La Antibodies)
Skin and nerve biopsy may be recommended after the results of these investigations.
This should give the diagnosis and guidelines for the management.
Following are the causes of neuropathy (many times cause is not known);
2) An underactive thyroid gland
3) Excessive use of alcohol
4) Thiamine deficiency
5) Vitamin B 12 deficiency (pernicious anemia)
6) Vitamin B 6 (pyridoxine) taken in excessive amounts
7) Drugs, medications, herbs
8) Autoimmune diseases
9) Heavy metals such as lead and mercury.
Please feel free for your follow up questions.
I would be happy to assist you further, if you need any more information.
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