Obsession over past events

I have developed lately a tendency to obsess about past, usually unimportant events. At times during the day i get obsessed thinking about an event that might have happened in the past -for example i try to recall what i did or said in a given situation some time ago, and the fact that i do not recall exactly what i did, makes me annoyed and gives me a feeling that i have lost, or do not have any more, control over my actions. It also causes me to stress without apparent reason.
This may sound strange, after all, why obsess with past events of no importance? I noticed also that this happens periodically and when usually i feel stress free. My opinion, is that I think i have a tendency to preoccupy myself with a problem, whatever trivial this might be, so that i keep my stress level up.
I even thought of self hypnosis as a solution to going back over an event i am obsessed with so, that i can establish what i did or said in a situation bothering me.
What do you think i should do?

[Roger Gould, M.D.]

The chances are strong that you obsess like this when you don't consciously feel stressed, but in fact, are fighting off some distressful thoughts in the present, that are now covered over by a preoccupation with the past.  You might consider a consultation with a therapist rather than a hypnotist.