Havana syndrome: Exposure to neurotoxin may have been cause, study suggests
Possibly related tidbit - I used to roll my own cigarettes when working in the field as a geologist, left a pack of papers under the seat of my truck which had no carpeting, spilled 100% DEET on the floor, DEET absorbed into pack of papers. Months later found those same papers (what luck!) and rolled a cigarette without thinking about it, minutes later I was asking my now wife if she "could hear the helicopter sounds!!?" and thought I was losing my mind. 
 I put it all together weeks later when I remembered the DEET spill from several months earlier. Pesticides/insecticides, in my experience at least, can induce those symptoms, lol - maybe the mosquito spraying was a little heavy by the hotel? And now I hope I don't have brain damage, thanks internet.