Angela, when i went to see the physio for my sore bum, she had a plastic pelvis, lol, and showed me what could have caused the soreness there.. basically, if you are lying on your back the tail bone is bent in a wierd position and it can sort of get in the way of baby coming out and the baby can push on it, kwim? She reckons that could be what caused my sore tailbone.
Anyhow, its much better now, but still a bit of pain depending on how I am sitting.