When our Macie broke her toe, she wasn't very sore right away. I think as she walked on it, the bone torqued and moved out of place. Sounds very like what you observed in Sadie.
If Sadie has osteoporosis, it's possible there's something broken. If it is, and it's not set properly, it could heal badly. The best way to rule that out and/or treat if it's broken, is to see a vet. Until you know what you're dealing with, it's going to be pretty hard to garner advice on how to treat it.
I hope she's better soon!