Heh, I grew up on the cape, too, but didn't get Lyme until I moved to NY. I think the link Lesley posted is a really good one - the problem is often that the screening tests are basically worthless unless you're in an obviously acute phase, rash, etc. and I think most mainstream docs will just stop there and not go further if you're negative. Then it can go the other way with the WB, and you sometimes get a false positive. So if you really think you do have it it might be important to find a Lyme expert if there are any on the cape, or maybe you could get to Boston or vicinity if there is anyone good around there.
Begin an intelligent person, you know that there are big variances between different ELISA and different Western Blot tests. So what holds true with one, might not with others.
That said, there will be published a study in 2010 where you can see that both
the specificity and the sensitivity is higher with the Mikrogen Western Blot, than for all the ELISAs.
ELISA tests often show a "serological scar" (often referred to as false positive) in areas with much lyme. Rates of around 1/3 of healthy blood donors testing positive with the ELISA is not uncommon.
Anyway, point is that the Western Blot does not have to produce more false positives.
And another point, which is off topic, is that I think that the 1/3 testing positive do in fact have a latent infection, but feel completely well (and will most likely do the rest of their lives).