So it turn’s out EFH wasn’t the problem.
Long story short, I’ve always had pretty severe insomnia and at the time I was using (abusing?) antihistamines to get to sleep. After that “episode” I swore them off but last week I came down with a cold and got really congested. I took this cough/cold remedy pill (which contained an antihistamine) and it happened again. Gotta stay away from the antihistamines.