Funny you should say that… I asked my T the same question a few weeks ago and she also answered with "ask your T"… (though I guess it goes without saying she'd say something like that…). She is indeed one of the main sources I use but sometimes I feel like she might not have an answer herself… though like you say, sometimes the same thing can have many sources…
My T is good at playing devil's advocate and asking leading questions... . not because he doesn't have answers, but he feels strongly that I need to figure out the answers myself. Do you think your T could be doing something similar?
The other thing you might want to think about is the possibility that you may not be able to pin this issue down to a cause. I know that would be very frustrating, but do you think you'd be able to deal with the issue if you aren't able to find a definitive cause?