There is Whipples disease, a gastrointestinal thing that can cause systemic and neurologic symptoms. I don't know much about it, but it is discussed in an article I have on the neurological manifestations of gastrointestinal disease. It is a rod shaped bacterium, I think.

Long shot? I don't know enough about it or your symtpoms to make a guess~
http://jnnp.bmj.com/cgi/content/full/68/1/2

Cara