I am exactly the same, though I do have certain triggers. I found this site in one of those very depressed states. I have been diagnosed with MDD by three different psychiatrists over the past 2 years but I have these moments when I think there is more wrong with me. I search for more thinking this cant be 'just' depression...its like I need another labelled disease to prove and answer my over worked imagination. My overall depressive state has been ongoing for over two years now with brief moments of happiness. Someone could say something to me that upsets me, then 'boom' I am back right in the dark hole. My sensitivities are extremely high all the time. I can break down crying at any moment....sometimes I truly have to force myself not to cry...that in itself is very exhausting. I have never marked my moods on a calendar...perhaps thats a good idea.