(just to bump...)
Anyone else experience this? Advice? Causes? :)
My wife and I are having the same issue. After running a 5K we can hardly sit.
If it hurts on each side of the tailbone, it might be sacroiliitis (try googling that). If it hurts right in the center, you might have gotten a fracture in your sledding fall. I would think that would have healed since then though.
My tailbone hurt for about a year after doing a flip into the shallow end of a swimming pool and hitting the bottom. But running didn't make it hurt. More like if I bumped it, or if I sat on a bike seat, or laid on my back.
I had problems with that while training for a marathon this year. It may not be the same thing for you but I was told it was my sciatic (sp?) nerve...worth getting checked out. A few massage therapy appointments and it seems to help me.
My bad, that I forgot to mention this. Very common with runners, due to impingement of the sciatic nerve by the piriformis muscle.
rmgarcia: Try the test that is described in the second paragraph of this article:
Also try googling piriformis syndrome.
it could be tight muscles including the hip musculature. I suggest seeing your doctor and perhaps physical therapy will be recommended.
I get it because I sit on my ass all day and then squat and pull.
If its just tight musculature, then get a tennis ball (to start with) and roll out your glutes. When it hurts, sit tight until (your eyes tear up) it releases. Repeat often.
When you are finding a tennis ball manageable, progress to a hockey (or lacrosse) ball.