I know a little about Fibro from m own lyme research. It is such a general non-specific diagnosis, you have several suspect pathogens that may be involved.
The first two would be what I would go after.
Lyme itself, using a natural antibiotic, since that is easy to get here in the U.S. Nutramedix Cumanda, or Samento will work enough to tell if it is Lyme or not.
The other suspect pathogen could be one of the Mycoplasma family, which like Lyme also weakens the immune system. There are a few different Mycoplasma strains, but Cumanda will kill them if it is used for a longer time.
There also is a DNA test for Mycoplasma which would be the first thing I would have done. The Lyme tests are unreliable at best, so I would get that test also, but not to rule out Lyme, but only to confirm if it is positive.
Dan