This disorder is called PTSD, or Post Traumatic Stress Disorder.
PTSD is a condition that may last a few months or even years, with triggers that may bring forth memories of the trauma accompliced with powerful physical and emotional tics. Symptoms of PTSD can include nightmares or stressful, unwanted and uncontrollable memories of the scene. Certain treatment options can include different types of trauma-focused psychotherapy and special medications to manage PTSD symptoms. PTSD is usually associated with war veterans and murder witnesses.
