Sorry you have to go through this again, but it’s pretty typical for PTS to get triggered again and rear its ugly head once more. The good news is, you know how to deal with it now, you sent your symptoms packing once, and you can do it again. The most common way people heal is this way - you learn your triggers and know how to respond to them quickly and efficiently, and the episodes become less and less frequent. One day you notice that you’ve been fine for months, even years. Sometimes people are fine for decades but it’s possible that something very intense - like open heart surgery for a World War II survivor - can bring out a reprise of symptoms for a brief while, after being quiescent for decades.
So don’t be discouraged. Go back to the self-calming, healing practices that helped you surmount this the last time. Read the book again if it helps to remind you of what you need to do and if it feeds your motivation, but it’s the guided imagery and all the other mind-body approaches described in there that will see you through this and get you back to where you want to be.
If you don’t catastrophize this (OMG, I’m never going to be healed of this!! I was kidding my self!!!) but see it as the normal course of healing, with bumps along the way, you’ll become better and better at subduing these pesky demons - more quickly, more efficiently and more skillfully. One day you’ll notice the nasty suckers are gone altogether.
And to answer the question about your cells - yes, PTS can get into your cells, but cells renew and change themselves every day, every hour, every minute. So don’t let that idea trip you up!
All best and stay in touch - I’d love to know how you’re doing in a few months,