You've received great information and suggestions from many, and like many, I completely agree with Jen's suggestions.
I lost my last girl to osteo. The vets were very clear that even at the highest dosage, there would still be breakthrough pain. I chose to let her go that day. If I were home on a daily basis, I probably would not have done it quite that fast but I was in the midst of packing the apartment to move across country and there was going to be too much change to her world, her pain, where she would sleep and how to get her across country for me to prolong her pain so that I would have more time with her. If you are home with Crouton, and can monitor her, then I would say give the higher levels of pain relief that have been suggested. If you see no improvement in her pain, then you will have to do what seems unthinkable.
Hugs. My heart hurts for you.