I would get another opinion from a LLMD if it were me. The usual problem is false negatives, not false positives.
Patsy10 is right, the tests are not very accurate, and a diagnosis should not rely on test results alone, but also on your history and symptoms all taken together.
Also be sure your LLMD knows where you have travelled, because there are hundreds of strains of the bacterium (Borrelia) that causes Lyme, and even in the US and Europe, the tests aren't able to detect many of them. It may also be true for any So. American strain you may have picked up.
Good luck, let us know what you find out.
Denny, my results were the same as yours (same band reactive positive on the WB, and the only one that was). My doctor insists that this is just a cross-reaction and that no re-testing as needed because if I had lyme, all bands would be reactive on the WB but then again he also says that the test isn't very reliable. Were you also tested for Epstein-Barr virus antibodies? I tested positive for antibodies from a past infection, not current, and my doc says this could be the reason for the cross-reaction. I am going to look further into it just to make sure.
Here is a link for you to read regarding explanation of the western blot from a LLMD.