I don't want to pretend to know what's going on in KDM's head, but as I understood it:
I was mild-positive for the elispot, but all the other test were not pointing to an active Lyme infection. He called it a hit-and-run, post lyme. The lyme came along and helped me get sick, but is not present anymore.
My interpretation is that certain infections are known for "helping" to get your immune system and gut out of order. There's post-lyme, post-Q-fever, post-viral etc etc. I can imagine that it's more important to treat the cascade of problems that this causes, than to know which infections caused the problem in the first place. Unless it's still an active infection.