Hi there, thanks for asking. Preoccupation about the past could be a sign of depression. Depression has several kinds like major depression
, minor depression, dysthymia
, etc and some of need medication while others are treated with talk sessions. As you mentioned stress
can provoke the onset of depression. It is very good if you practice some methods which reduce your stress level, like Yoga, etc adn if you still feel that situation is not getting better, you can take advantage of consulting with a psychiatrist
. I wish you the best health.