They were a recurring thing all through highschool, undergrad, etc; and tended to come in clusters/cycles: pretty frequently for a few weeks/months, and then not at all for a few months. But prior to monday it's been a very long time since I had one (even with those cyclic breaks in mind)— to the point where I was hoping/thinking they were gone. I really hope this isn't a sign that the cycle is starting up again