I think Knot is right about the "tipping the bowl" pelvis tilt thing, Suzie. The fact that your sitbones haven't gotten sore at all on your new Brooks, but your girly bits are very sore, strongly suggests that you are not tilting your pelvis in a way that puts your weight on your sitbones where it belongs. Do try to tuck that tail bone in and under, consciously put your seat weight on your sitbones by tilting your pelvis and pulling your stomach in. I like that vision Knot described of keeping your pelvic "bowl" from tipping water onto your top tube!