you havent had the best run lately have you hun,

Nearly all my labours where in my back and that was my first hint, at the real thing..
Could you ring them up and just chat with them and see what they can provide in way of info etc?
Could you have a UTI? an infection can run havoc on your body while pregnant..
I also agree, a nice hot bath and then lay down somewhere quiet and tune into your body and see how far apart,length between and during and pain on a scale... that way you can sort of see if you should be alarmed etc..
Fingers X'd its just the bubs playing hopscotch on your pelvic are, not nice i know, but happy thoughts being sent your way.. xoxo