Contact with farm animals? Could you have gotten contaminated by chemicals in a barn?

A lot of docs blow off Igenex Labs, but they are CLIA certified, and they do the bands for Lyme and Erlichosis. You could try that. My IgM response to Lyme was high and they only do the IgG on standard tests. I had PCR of my CSF and it was negative, so I am reasonably sure my Lyme was killed...but it may have induced the autoimmune stuff, I don't know.

Also, they can do a biopsy of muscle to see if anything shows there....I surprisingly showed a neurogenic myopathy.

I imagine they will do a skin biopsy and also stain it with the Congo Red for amyloidosis.

What is odd is your issues proceeded in a cephalic to caudal manner. Really odd. Guillain Bare goes from lower to upper. Most PN is distal to proximal. You are a mystery!!

I just think it is likely some organism, just as the others do. I would exhaust that first, the other things will eventually become clinically evident.