Yesterday When I Was Out To Eat My Brain Went

Yesterday when I was out to eat my brain went kind of fuzzy, then within 4 to 5 minutes I had an episode of chills, that i kind of felt build up and then release as chills, after o was incredibly exhausted but my head slowly became clear. I've had these chills before and I can usually feel it building and fight it off for a bit but it ends up releasing at some point within minutes and lasts just a couple of seconds. They seem to be getting more frequent and most of the time happen right after mild anxiety causing things. Like someone walking right behind me. Or passing a cop when I'm going a little too fast.