so it's a trauma response, but don't treat it like one with the whole "Oh, it'll go away" whenever they have an episode. what you really need to do when they have an episode is (Imo) have them maybe sit on the floor, and if it's available wrap them in a blanket. I'd treat them like the general age that they regress to, instead of a teenager. I'd crouch beside them and say things like "It'll be okay, sweetie. everything will be okay." and maybe give them a hug or something.
(PSA: not real medical advice, I didn't do as much research for this one as i do the other things. I'll come back when I've done a little more research.)