You've been framed.

There was a man in a drama on the the telly the
other night who had been framed for murder.
He could remember what he was doing and who he
was with on a particular day, 3 months previously.

I was thinking, hang on?
On a day to day basis, I can hardly remember my own name
or where I live, on a good day I know where the toilets
are and how they work. On a good day.

Turned out he was guilty. Obvious really.