Your symptoms sound classically like herpes of
the nipple to me. The culture was positive because it is herpes (very likely HSV 1) and the PCR is not a test for
herpes in the blood and I have no idea why it was done. Are you sure it wasn't an antibody test from the blood? I would expect, since this sounds like your first infection, that this was an antibody test, not a PCR test from the blood, and that it is negative for
HSV 1 and 2 because this was your first infection with HSV.