OK, with our wifi down I am sending this from my Blackberry via email.
I had an interesting Pilates mat class this morning. Only one person who does mat class at home but it is making her neck and back pain worse. She goes because her friend teaches the class.
The first thing I noticed was that in an attempt to keep a neutral pelvis she was tightening her entire back to shove her ribs up. Her abs were barely engaging even with her head and legs up!
So we worked on relaxing the ribs and letting them move. She felt her abs, her neck was better, and all the exercises that had been impossible were at least in the realm of possible!
Pilates shouldn't hurt. If it does you need a new approach and/or a new teacher.