I think I broke (or at least cracked) my tail bone back when I got my first horse. I was riding bareback, someone slammed a car hood or something, he jumped and I landed flat on my butt. It hurt for months. I never got it diagnosed, but I was in high school at the time and they had those awful hard seats that are attached to the desks. I eased myself into those desks like an old grandma for a long time. So I feel your pain!
I still own one saddle that if I ride in it too long hurts my tail bone. But my main saddle is fine. So maybe it wasn't completely broken, or maybe my current saddle just fits me good.