D..
Your tailbone may be in a different "place" after the pregnancy and giving birth. I pushed mine into a 90 degree angle when I was in 7th grade by falling on it. The regular doctor told my parents that I would just have to take a pain reliever every day for the rest of my life, or have my tailbone removed surgically. Well, forget that! Instead, my dad took me to a chiropractor who pulled it back out where it was supposed to be and I sat on a split cushion for 6 months. I've never had a problem since.
You need an xray to see where it is positioned, D., first of all. Then go from there.
Good luck!
Dawn