Like adult post-trauma reaction, PTSD symptoms may appear immediately after the Acute Stress phase completes, or later after another triggering event or experience. Note: many of the signs of PTSD in children can look like a different issues. Common misdiagnoses include ADHD, ODD and Bi-Polar. Many PTSD victims (and this includes children) hide symptoms and do not disclose the fact of the trauma. This means a child could go struggle with symptoms for several years before PTSD is diganosed.