i think it is "normal" in ptsd.
normally everyone of us act in the present on the basis of the past, using the past experiences to react in a new situation when we recognize similar characteristics. it's the process of learning. it' our intelligence.
this i have described is a normal path our brain follows, from the past to the present.
what you are talking about is a process from the past to the present too, but in a sudden way, so sudden and violent that you don't remember when it appens. this because your mind really can't stand it!
what you have to do is, whit the help of your therapist, to slow those scenes down, in your mind, so that you can learn from them and go ahead.
and when i say "learn", in this case i mean "recognize everything".
it is painful, but it is the only way..
have you ever attended a course of personal defense?
ciao!