Hi Recall.
Yes. That can occur. Triggers occur due to a trauma or fear or both.
Yes. Deep Breaths, Slowly. Three times. It sends oxygen to the brain which in turn relaxes the mind and central nervous system.
Tell yourself it is not real. It already happened. You got through it. Your in the present.
Or if your in an opportune place when it occurs, yoga, meditation. Meditation can be as simple as returning to a happy moment in your life or allowing your mind to go to a favorite place, under a palm at a beach, and just allow your mind to relax.
Hope this is helpful to you.
Chickadee