I'm 75, and have gone through several painful surgical procedures.<p>There is no pain worse than a cluster headache that I have experienced, so far. The only good thing about a cluster headache is that each one only lasts several hours. The very bad thing is that they come on like clockwork, at (for me) 1pm every day for months.<p>For me, they are stress induced. Luckily, I have not been stressed badly in quite a while.