>>116219
It's probably a painful memory. If you carefully examine your thoughts and emotions around the feeling, you'll be able to spur recollection. If you or somebody uttered phrases at the time, you probably repeat them all the time. You're also probably obsessed with avoiding similar situations now and may find persons or objects repulsive, or unnaturally attractive.
Record your thoughts, memories, phrases, objects, feelings and gradually build full recollection over time. You'll only get tiny fragments, then finally the big show, if it's really painful. I don't think there's any other way to tease memories out.
Some people like having another person help reconstruct the event, like with a therapist or whatever. I don't think other people are necessary, but I can see how it might help. Simply being around people makes me feel all sorts of things that are difficult to reconstruct alone, but I don't trust anyone like that, it would be life ruining to have some secrets escape. I do like to secretly glance subjects off people when I'm trying to remember. They don't need to know the role they're playing in my mind, just create a similar feeling to remind me.