Hello and welcome to the forum. Sorry for a delay in response. It can be difficult to diagnose for Lyme's disease, unfortunately. The tests look for antibodies and you can indeed have antibodies in your blood for months or even years after an infection. However, I would think with your history of symptoms and the positive marker that further follow up would be warranted. https://www.lymedisease.org/lyme-basics/lyme-disease/diagnosis/. Please note as well that the CDC recommends a two tier test system for Lyme Disease and that many people with Lyme initially test negative. I think a follow up with this doctor or another for another opinion might be in your best interest.