Sounds like you are getting the runaround with your lab results. What test specifically were you given? At what lab was the test performed?
It is true that especially people who are immune compromised that other illnesses/infections can be activated (mononucleosis is an example, for one). It's also true that many people have the lyme spirochete and are completely asymptomatic.
Both of the tests I took didn't have an "unrelated spirochete" section. The first test I took they actually used darkfield microscopy to photograph the spirochetes in my blood, and used a dilution rate to determine how many of the spirochetes were present.
The second test I did tested for certain proteins realted to Lyme, and at least one of those I tested positive for was Lyme-specific.
These are the only two lab tests that I am aware of that are in any way accurate, and a lot of people who are sick with Lyme have done a lot of research on how they work and why.
I feel really bad that you had that experience. If you care to share a bit more about the test and what it did maybe it might help figure things out.
I realy hope you get some answers. It is so frustrating being sick and not being able to trust what your doctors are saying.