I'm sorry I can't be of help with this personally. However I noticed no one had yet replied to your post. So I thought I would. Hopefully there will be other members who will yet have some helpful suggestions they can share. In the meantime, here are links to some articles, from PsychCentral's archives, that hopefully may be of some help:

Understanding the Effects of Trauma: Post-traumatic Stress Disorder (PTSD) – Psych Central

Why Do Flashbacks Happen? | After Trauma

Coping with Flashbacks – Psych Central

What is a Trigger? – Psych Central

What Triggers You? – Psych Central