I have something similar that happens in the middle of the night when I am particularly distressed (not related to a loss). When I told my therapist, she said she didn't know what it was, and referred me to someone who could explain it (if I wanted evidence that it was "something" people experience and not my imagination). The main thing was, she didn't invalidate it or have an interpretation that was opposite to my feeling. We addressed the feeling. Maybe that's what you could ask your therapist to do? That way, she can't really tell you you're not feeling what you're feeling if you take out the event part of it.