Gland damage would show up on hormone blood tests. Does CFS always start with an infection? Are there any particular suspect pathogens? Lyme Disease? Any others? If it is an immune response then it could be triggered by a whole host of different little horrors.

Whatever's wrong with me came on slowly over months and initially presented as long sleeping and bad hangovers, followed by alcohol aversion. (I assume I was learning to avoid it) One of the major differences NDT made to me is that I went from '2 pints gives me a three day hangover' to 'a huge session makes me feel slightly woozy the morning after'.

I did get a tick bite years ago, but there was no sign of Borrelia Burgdorferi either then or now.

I did read a paper a while back claiming that there must be a second cryptic pathogen from ticks, because the symptoms often appear without the spirochete. All that might be worth a look.

EDIT: Actually that's not true, according to my own blog:

http://johnlawrenceaspden.blogspot.co.uk/2012/09/ok-nhs-is-brilliant.html

At the time I wrote that there was a bloody great rash. But the test then didn't show the infection, and this summer's tests didn't show it either.