A quick Google search found this list. Most of these conditions are very rare:
Acute Disseminated Encephalomyelitis
Adrenoleukodystrophy
Adrenomyeloneuropathy
Chronic Axonal Neuropathy or CAN
Chronic Inflammatory Demyelinating Polyneuropathy or CIDP
Chronic Relapsing Polyneuropathy
Devic Disease
Guillian-Barre Syndrome or GBS
HIV induced CIDP
Leber’s Hereditary Optic Neuropathy
Lewis Sumner variant of CIDP
Multifocal Acquired Demyelinating Sensory and Motor Neuropathy or MADSAM
Multifocal Motor Neuropathy or MMN
Multiple Sclerosis or MS
Neuromyelitis Optica
Paraproteinaemic Demyelinating Neuropathy or PDN
Tropical Spastic Paraparesis
The list came from the "Demyelinated not Destroyed" blog site:
http://www.demyelinatednotdestroyed.com/list-of-diseases/
Good luck with your doctor visit.