It sounds like intrusive thoughts/memories that upset you until you have anxiety or panic attacks.

A flash back is when you go back to the time of when the trauma took place and relive it. It feels as if you are there in the trauma issue, and not here in the present. It's hard to speak to anyone and snap out of it and takes a lot of work to be able to bring yourself back (if it's a long flashback)

Take care
Tammy