A concert is a choreographed harmony of sounds but throw the prefix "dis" in front it and you have the opposite: disconcerted — a word used to describe someone whose composure has been disturbed or unsettled.
Disconcerted is a combination of the French prefix des- which indicates reversal and the word concerter meaning "bring together," so something disconcerted is not brought together, but rather torn apart, or thrown into confusion. If you are under a lot of stress or worried about something, you're in a disconcerted or discombobulated state. Take a breath. Relax a moment. Everything will be OK.