Hey Z,
That is some crazy bad luck you're having - with the 2 uncertain tests now.
I used to run tests like the b27 when I was working in a med lab for awhile. The "uncertain" usually refers to when the test isn't quite making the minimum required (and accepted) levels for a positive (or negative) result. Could be faintly positive, or it could be a messed up test. I'm guessing it wasn't negative and it was "almost" positive according to the accepted numbers. Sort of like a test stating a little bit pregnant, but not quite positive. lol I just can't believe that you had the same result twice!
I also can't believe your doc was so unfeeling to say you worry about it too much. Even if you did worry too much, saying it that way isn't going to help matters! That's just poor form.
Hang in there, hopefully the next lab will figure this out.