Mom diagnosed with Cancer of Unknown Origin with lesions spreading in Liver

My mom was diagnosed with Cancer of Unknown Orgin at the beginning of Sept. She was having this terrible back pain, went in for a scan and they found a tumor on her back (causing the pain) and 11 lesions in her liver. They immediately did radiation on her back and chemotherapy. We received the results back a week ago that while the tumor on her back is dead, the chemo did not work for her liver (since they cant radiate her liver). Not only did it not work, but the report says that they have 'increased significantly'. We are exploring other options at this time but she has lost a lot of hope. We've dealt with cancer in the past and we know when things are not going well. I called up CyperKnife, which is this newer option that is supposed to be able to do very specific radiation. So i was thinking that they could just do that on the lesions on her liver. But when i spoke with the nurse today for an over the phone consult, it didnt sound very good - seems there are too many (but they are looking at the scans) - I wanted to know if anyone is familar with CyperKnife or my mom's type of cancer and what their thoughts were. I've been reading up on it and all the survival rates are not good - in line with 3-4 months. She is only 51, with 4 children and she is not ready to die yet, nor are we ready to lose her. If any one knows of the best specialist in this field, please let me know. We are desperate at this point. Thank you very much.