Scombroid food poisoning is, I believe, the answer to yesterday's question! Or at least that's my theory. It's not an allergy, but a very specific pathogen found in the skin of certain fish that only creates toxins if under-refrigerated. Cooking kills the pathogen but not the toxins. Not everyone responds to it, and it is usually self-limiting. Benedryl (anti-histamine) is often recommended.
That was such fun, I'm going to do another. One that took me two days to find a few years back, but turned out to be true Two siblings, both early teens, started to have similar strange "episodes." One was a boy who lived for video games. The older sister had just learned to drive. The boy would come to his mother in terror because he'd felt as if he was frozen and time stopped - then he'd awaken and be exhausted - afterwards he would sleep for hours. The young lady had to pull off the road while driving because she experienced these moments when everything became explosively loud and then inaudible, time would speed up, and then slow down - and she felt very disoriented. There were no other symptoms or problems. The doctors could find nothing. The kids were otherwise healthy. The episodes became more and more frequent. The boy's episodes decreased after his video game time was limited.