Sometimes Ativan will take an hour to work, unless you dissolve it under your tongue. ( it bypasses your liver and goes right in your system).

Meanwhile, try not to hyperventilate. That will make you dizzy and make all of your symptoms worse. Breath in and hold it for about 2 seconds and breath out slowly like your breathing through a straw.

You've done this before. You know you're not dying. The Ativan will kick in eventually and you'll be fine.
Stay here with us until it passes if it helps.