A friend of mine has it, and it causes periods from hell 4 or 5 times a year. Found this web site which points out that sex during and/or after can cause pain. Also it notes that the amount of endo doesn't determine the amount of pain.
The above mentioned friend takes Darvocet during the more difficult times. Avoid the recent nsaids such as Vioxx that are getting some bad press right now for "we shan't mention them in public" side effects.
Keeping her fingers crossed for quick resolution for the Honeypot parts.