Yes, if we start talking about childhood. It just happens, and then only later can I figure out what might have triggered it. It's usually this feeling of intense loneliness, from when I was little.
It's taken me a while to feel comfortable with it - the main problem being that crying in front of someone sort of presumes that they give a **** about your feelings. Which is a lot to ask when you have really low self-esteem. But I've struggled through it, hoping it will pay off somehow.
"Sometimes I wonder how all those who do not write, compose, or paint can manage to escape the madness, the melancholia, the panic and fear, which is inherent in the human condition." ~ Graham Greene
My heart aches, and a drowsy numbness pains
My sense, as though of hemlock I had drunk,
Or emptied some dull opiate to the drains
One minute past, and Lethe-wards had sunk