Damn, OP, I'm sorry you suffer from PTSD, but you shouldn't blame yourself for the Rock Boy's death. It's the fault of human nature, people are behaving horribly with other creatures, and it is not much you can do about it. From what you described, your actions after the war have turned against you, but maybe you can reintegrate or at least raise awareness by sharing this story.

However, I'm a bit skeptical about Dr. Yuger; I feel like he either thinks you're crazy or tries to hide something. Have you ever considered revisiting the mountains if you had the opportunity? There's a chance that Nails and the other polyglots have learned to avoid humans, and maybe they'll remember you and come out of hiding.