--but the acute onset, and the widespread nature of the symptoms, makes it more likely that this involves the central (brain and spinal cord) rather than the peripheral nervous system, especially since you mentioned the epidural . . .

A work-up for you should probably start with MRI's or the brain and spine, to see if there is any compression or demyelination there. The disturbances of sensation you describe could be stemming from the small fibers, but they might also stem from the central nervous system (and the symptoms of disruption to either might be exactly the same).

If small fiber dysfunction is suspected a skin biopsy to measure density and condition of small unmyelinated nerve fibers, or at least some form of quantitative sensory or autonomic testing, may have to be done--standard nerve conduction/electromyelograph studies can only measure activity in larger, myelinated nerves.