POST TRAUMATIC STRESS
If you have experienced a trauma that continues to cause you problems such as nightmares, flashbacks, heightened anxiety, a negative view of yourself that has impacted significantly on your life so that you are no longer able to do some of the things that you used to enjoy then this can change.
No one is immune from getting caught in a moment that leaves them traumatised and experiencing PTSD. You would have experienced other traumas in your life that have long since been forgotten and never cause you any current problems. That is what the brain is meant to do with trauma so that you can carry on your life.
However, with PTSD the brain has not done the necessary processing of the trauma to allow it to be stored as a memory that no longer has a debilitating emotional impact preventing you from living your life as you would wish.