For what it's worth, Lyme disease testing is tricky. One of the better labs that regionalizes their test assays (for different microbial strains) is:
Welcome to IGeneX, Inc.
They also test for many other kinds of bacteria that can be carried by the ticks (bartonella, babesia, etc.). Those co-infection by themselves can cause DDD and have been found in spinal discs. I don't think they test for protozoa and other tiny creatures that have been found in many patients with DDD.
A potentially flawed blood test (or truly negative test result) is only one data point for a doctor -- a trained professional that understands Lyme disease uses a thorough patient evaluation to come up with a clinical diagnosis. It's not just a blood test. See:
http://www.ilads.org/
Once bugs get into the blood, they don't just sit around and wait to be gobbled up by the immune response. Many gram negative bugs actually "feed" off the immune response! They have thousands of defensive and offensive survival mechanisms, which is why blood tests don't always hold the answer -- especially if they are based on culturing.
Thankfully, newer molecular diagnostics are getting better every day and telling us stories we never thought imaginable.