Used to get clusters about 6 or 7 years ago. As Adam mentioned in his post above, the pain of clusters is almost cartoon like in their ability to go from 0 pain to tear-your-face-off-pain in a few seconds. I got them mainly (99% of the time) on the left side of my head, felt like someone was literally trying to stick an ice pick through my head behind my left eyeball. My doctor prescribed
Kapake (mine came in a little packet you mixed with water and drank instead of in tablet form) and it worked really for me.