--this is apparently approximately what happened to me: an acute onset (hours/days) rapidly spreading small fiber neuropathy that began distally but eventually encompassed the whole body.

Not a variant of Guillain Barre syndrome per se--Guillain Barre is primarily a demyelinating process, and this by definition involves an attack on the small, unmyelinated sensory fibers that subsume the sensations of pain and temperature (and most autonomic functions)--but analogous to it in presentation.