Yes this has happened me too a few times,
I have noticed that if I had a square or 2 of dark chocolate,I would feel euphoric for a few hours.last year I did this every day for a few weeks and when I stopped one day I really paid for it.
felt really ill,phsically,mentally,felt so awful...
Strange thing is the last time I ate a few squares of dark choc,I didn't experience the euphoria or the crash later,it's been 3 months since the last amalgams were replaced,I wonder if my body is more able to handle things now,maybe I'm finally healing.I was also able to tolerate a slice of rye bread last week,which is incredible,I could not tolerate any gluten or gliadin grains for years.