I have experienced many things like the poster described. I believe it to be the effects of dissociation and/or depersonalization, derealization. One of the hallmarks in dissociation disorders is the inability to distinguish between thinking something happened and it actually happening. Like locking your front door and then a little later doubting that you actually did it, that maybe you only thought about it, or remember doing it the night before. And the foggy headed thing i remember describing to someone as if my head was a helium baloon tied to my neck and floating in the general vicinity of myself. The feeling of unreality.