I sometimes have had truly awful post session hangovers. There was usually something specific that triggered it. I also have felt that the main way to manage it was to just wait for it to pass. I tried intense exercise. I’m not sure that that really helped. Yoga might have helped. I view it as comparable to a flashback in PTSD. I think that something in the session triggers it, and I’m then taken back to something from my childhood, and I get a re experiencing of the awful emotion from that moment.