Based upon purely personal experience most likely, but what would you vote as being the worst experience of pain that you have endured? Like most no doubt, I have endured enough physical pain but I probably wouldn't class this as being the worst even if some such was bad enough at the time. And I will have endured many others on the list too.
If not on the list then please add whatever is appropriate.
If not on the list then please add whatever is appropriate.