People who say “Calm Down”” don’t have a clue. Once you’ve reached that level of excitement, those words don’t register, and if they do, they provoke you even more because your brain realizes that’s not an option.
Rudyard Kipling wrote, “If you can keep your head when all about you
Are losing theirs . . .”, you’ll be a man. So what are you, if you’re the only one losing your head? Maybe you’re more tuned in to danger than the rest? At any rate, “Calm Down!” is the worst thing to say to someone who is very upset.