One of the things we fans love is our Woobbie Heroes, the guys (like Daniel Jackson or Bucky Barnes) who suffer so beautifully. Hurt-comfort, we loves it, precious. (And oh, I am dating myself with those terms.)
Anyway, there are a lot of fics about, say, Bucky recovering from torture, or where his psychological recovery is a large part of the story. And one thing I've noticed is that the treatments for PTSD that people normally use are behind the times. Like, they'll have talk therapy, and maybe a therapy animal or journaling--and these are good and helpful--but there's been a LOT of research into trauma disorders and recovery in the last two decades, and a lot of developments of new treatments. Talk therapy is not the gold standard of what a cutting-edge therapist recommended by Tony Stark would use. It might well be part of the therapy, but not the whole of it. And Sam Wilson, working at the VA, would certainly know this as well. I am not a professional, but I have read enough of the top books on trauma to have some feel for the subject.
If you would like to incorporate some more current research, understandings, and techniques, the best place to start is The Body Keeps the Score
by Bessel van der Kolk. He's got decades of experience and research dealing with combat vets, survivors of childhood abuse of every kind, and every sort of trauma you can imagine. The book is well-written and interesting and suitable for a non-specialist to read, and it covers the history of trauma in psychology and how we learned what we know today, along with some very interesting case studies. Best of all, the last few chapters are overviews of what he's found to be the most effective forms of treatment, including a brief overview of what the treatment is and their best guesses as to why it works, and then some examples of what's happened when he has used it or seen it used. (Also, it's fun how he burns the DSM-V and some of his colleagues. Like, there is SO MUCH SHADE, OH MY GOD.)
If you want some medical jargon to use in your fic, the place to start would be The Body Bears the Burden
by Robert Scaer. Scaer is a neurobiologist, not a psychologist, and boy howdy can you tell in his writing. This one is a little more challenging, but it has a lot of medical stuff if you want to use that in your fic and wikipedia isn't doing it for you.