Well, not quite arse ache, but pain in the area I've highlighted on a helpful visual aid 
So I'm 11 weeks and yesterday noticed I was having pain in the area I've drawn. It's not cramping nor constant, just the sharp achiness you normally get when you've pulled a muscle.
It's worse when bending over or putting weight on my right leg, though I can still walk fine (though I've noticed my right knee has buckled a few times and I've nearly gone arse over elbow
Related?). If I'm standing still or sitting it doesn't hurt.
I was twisting quite a lot at work yesterday so perhaps that was it? It's not the dreaded SPD already is it? 
Thanks! 