I don't think it always works that way. There may not BE "that one call that caused it". I can't give you one, specific incident. I had a good friend who came back from 2 tours in Iraq & one in Afghanistan with PTSD. I think he had it when he came back from Iraq the first time, but he wasn't diagnosed until much later. There wasn't one incident, but the place he was at was called "the mortar capital of Iraq". He argued for a long time that "nothing all that bad happened". I'm glad your T gets the honesty thing and is going to help you with this! This is kind of why they're thinking there's a such thing as "complex" PTSD. Not one bad incident, but a lot of chronic stuff & there you go.