Commencement de la fin

There really should be a word that describes the feeling of running full tilt into a brick wall that you experience on return to work after having a break long enough to remember what being sane is like. I tried the thesaurus, but it was sadly deficient in suitable lexemes or indeed even morphemes. Apart from 'crack of doom' there wasn't anything there that even came close to describing the feeling I was after. I found something in french, but then got distracted ranslating stuff in google translate. For example 'au diable, vous et vos stylos'... I wish I could rant fluently in french