I relate. I've have the impending-doom feeling my whole life.
I am choosing today to think of it as anxiety that never got addressed. High-functioning, you know.
A slightly different version of this is "knowing" that someone is thinking ill of me or has made a decision that will affect me in a negative way. I call it my spidey-sense. It's from a childhood of waiting for the other-shoe-to-drop. It's like a heightened sense of smell. (See also: pre-spanking, lull-before-screaming.)
I've been praying for my HP to replace my doom-feeling with contentment.
I am pretty much relieved of it happening upon awakening. It is certainly a lot less present in the past 5 months than the previous 43-odd years.
There is hope!