Hey Mel,
Lets hope that you do go the whole way! That's great that the pain has settled down for you too. I'm sure that the sonographer would be able to see if anything was amiss, maybe just let him/her know that you've had some lower back pain. The stretches that Laranna mentioned would be great to do too, especially since it is always good to spend lots of time on all fours in terms of positioning of bubba in the final trimester. The other stretch you could do to help with the pain near your hip joint is a glut stretch. On the side that you are experiencing the pain, just rest your ankle on the opposite knee and lean forward. The tail bone pain may be due to it moving out in preparation for birth (which it is supposed to do to make room for bub to come sown the birth canal).

Hope the back pain continues to feel better!