I hope this isn't too speculative, but the way she walks and the fact that she did not report her afternoon absence at a new job, I'm inclined to think that she's stoned on something - perhaps an involuntary experience during lunch. When she seems to look around, as though trying to figure out where she is, that seems more stoned than drunk & stumbling. My impression is that either she has never been at that place before, or she has and she's disoriented.