Possibly new culture
There are many tests for lyme, but none are totally reliable.
test is positive in about half of those infected. The western blot test is positive in ~70% of cases, but most labs don't do a thorough enough version- i recommend igenex labs. Pcr tests are positive only ~20% of the time. A new test, a culture by advanced laboratory services may detect lyme in >80% of cases so may be best.