My first ended up being b2b and the pain was was all in my butt. It was horrid but also ended I a emergency section as I just wouldn't dilate passed 6cm
The likelihood is baby will turn, they turn all the way through labour as they negotiate the widest parts of your pelvis with the smallest diameter of their head. It is possible to have a baby born vaginally, back to back, you tend to feel most of the discomfort in your back/bum though
Spinning Babies!!!
I gave birth to my 1st sunny side up which meant back labour which was very uncomfortable. On the basis that baby might stay this way I defo recommend tens and counter pressure as a way to support the contractions. Good luck!