If you can’t know for sure what the trigger is, then having a ground will help. It also helps to look around and note what’s happening around you.

If you can’t tell anyone, writing it down is a good alternative. I suggest keeping a flashback/dream diary. 

I’m not forcing you, but when you’re ready it will help tremendously if you tell someone–a close friend, an adult, anyone–about what happened. You can find closure this way and will help you move on, thus lessening the nightmares/flashbacks.

Just remember that they can’t hurt you.

Sincerely,

Elle