Unresolved trauma is actually pretty easy to see. What you have is a real change. You have a kid that has been eating well, sleeping well, and being normal. All of a sudden, they are zoned out, out of focus or they are over the top, hysterical. Those would be typical red flag, type behavior. Something has happened, that has so upset this child, that that it has caused their nervous system to go off the charts. They are stuck in a place where they don't calm down, they don't get connected to you. If you are in touch with this child emotionally, and you are sensitive to their cues, it's pretty obvious that something is wrong. It isn't that hard to correct, because even when the child doesn't have the language, you can invite play. You can make space for them to communicate to you, what's upsetting them. Even if it isn't clear, in words; they can see that you are connected to them emotionally. That is usually enough to get them to normalize and get to see them the way they used to be.