@lisalucier nice list of possibilities. However, it’s just a start. @dailypain as mentioned to @vklittle61 could also be nerve compression (not nerve damage) resulting from myofascial pain. In other words, it can be reversed. I mostly had sitting pain but had whole chains of trigger points up and down legs and I believe into my psoas muscle. Let me tell you, when you have tension where a nerve plexus is (lumbar plexus goes thru psoas) you get some other weird effects, too. I described how I got rid of mine (my pain and tension) by stretching and exercise in replies to @bkruppa in the pudendal nerve entrapment thread of this website. This does not show up on imaging. As the authors of “a headache in the pelvis” state, it’s something like 6 years average before a correct diagnosis is made. Meds like nortryptyline can help calm nerves but stretching and exercising and very deep inspiration and learning relaxation techniques can largely get rid of this. Please see my prior posts in the pudendal nerve entrapment thread for the details.

@travipr and @dailypain @blue717 @danny67: Here are the things which have caused and still can cause unbearable pain in the sitz bones:
1) HIPS WHICH NEEDED REPLACEMENT! The doctors can't see all the areas where the cushion is eroded. I suffered for years. Dr. did the first hip replacement which helped - I ORDERED him (handed him a check!) to do the second one which solved that problem!!!
Here are the things which caused and have caused unbearable pain in the sitz bones:
The doctors can't see all the areas where the cushion is eroded. I suffered for years. Dr. did the first hip replacement which helped - I ORDERED him (handed him a check!) to do the second one which solved that problem.
2) Piriformis Dysfunction - what do I do for it? periodic steroid or NSAID injections (Toradol) over the years
3) tiny muscles/connective tissue off the spine aside the tailbone What do I do for it?
A) lay on dogs little rubber ball and roll around a few times a day for a few days
B) Stretch by sitting on a chair bending my left knee out and lifting left ankle over the right knee and pushing down on the left knee GENTLY. It burns like a $#@%*!!! do it a couple times a day for a few days. (mine is primarily on the left side. Do the right side or both.
C) Go for MFR! (read Mayo Clinic category on this!) It is NOT massage therapy. Kiss some frogs before you find your prince therapist on this. It is so painful but he found the area which is the culprit. I was heading back for another lumbar surgery. It stopped that in its tracks. Its weak muscles/connective tissue problems and a curved spine PLUS sitting too much over my lifetime. The muscles are trained to hold you in position to sit. When we age they have to work too hard. After MFR if I sit they snap back into painful spasm. I have to keep on with regular MFR and improve my sitting habits.
4) Botox! (covered by insurance! It paralyzes those little muscles snapping into spasm for a while.
@dailypain - in California where I live you get disability and medical coverage if you must quit your job. I hate to tell you this -- but your "job" might be causing some of this. Mine was!
I have always seen in my life as tragic as it is when one door shuts another is opened - even if I can't see it. I hope it will be the same for you!
Some of these things have resolved but then I go back and think I can sit again for hours on end and I put myself in the same jam. Double-check what you are doing. Doctors can only give medicines because people are stubborn and won't make the necessary lifestyle changes. 😉