I had that exact same thing for a few weeks, when I was experiencing the onset of my depersonalization and I was really freaking out. There's probably a relationship between anxiety and depersonalization, like how Diego said the effect becomes more acute during presentations. Like Aridity said, the best thing you can do is try to relax. Relaxing won't necessarily make your depersonalization go away but it will help your health and sanity in the long run. Almost nobody on DPSH has brain damage, and I assume you've been medically cleared, so that's your anxious mind coming up with scary scenarios. Stress and anxiety can definitely harm the brain, but it's not damage in the sense of having a stroke or hitting your head. The way the brain functions under anxiety changes, and that's probably what you're experiencing. If you're really spooked you can get thyroid and hormone levels tested, or a brain scan, but I think they'll find nothing.