Sorry to hear about your mom. My mom has exactly what your mom has. She has mets to 2 vertaberates. She had pain on the lower back and ended up getting radiation therapy for it and although she was very tired (fatigue is also marked as a radiation side-effect) after a couple of weeks, the pain was gone.
My mom was diagnosed with Stage 4 NSLC and went through Carbo platin and taxol with avastin, it worked while she was on it and then after 3 months being on maintenance on avastin her cancer showed progress to her lymphagenic pathways. She is ona trial study now but her next option would be Tarceva. Her back is again hurting and looks like another tomor on the bone, we are looking at another cycle of radiation.
My mom;s oncologist tells me that he has two ladies on Tarceva (stage 4 lung cancer) for the last 2.5 years. So there is hope.
Good luck.