Bartonella testing is as bad as Lyme testing. You might want to do some reading on Dr. James Schaller's site:
www.personalconsult.com/, as he has done extensive research on Bartonella (and Babesia).
Is it just the one lymph node swelling? If there are more swelling - even if they aren't as swollen - then it could just be your body trying to sort out the toxins from the blood. That's one of the main 'jobs' of the lymph glands. I had to take a tincture that my doc made to keep my lymph glands from looking like baseballs! And they were swollen all over my body, but the ones in my neck were by far the worst.