Doody,
Could it be coccydynia? Just a thought.
Also, I was having that same exact pain and to make a very long story short, I have three issues going on.
One, L5/S1 facet degeneration
Two, Rectocele
Three, Weak Pelvic Floor
So, according to one doc, this can all tie together. I am to get a facet injection next month. If that works, I am going into PT to work on the pelvic floor business.