livnah, I just want to specify that with flashback I don't refer to any memory, for I too experience probably hundreds of memories in a day. I am also a visual thinker, so there is anyways a constant visual imagery filling my mind.
To me flashback means something else. It's hard to describe it though... There is strong emotional involvement, like you would be experiencing it all over. I guess it goes with trauma or very strong positive emotion.