I am very familiar with this type of cancer. My mother was diagnosed 6-6-08, it had metastacized from her colan. My mother's pain had already began when she was diagnosed, that was the reason for the doctor visit. Her progress was very quick from then, even though the doctors gave us false hope, she passed on August 26, 2008.
She had many different symptoms for the last month, but the one that hospitalized her several times was the fact that she was having trouble breathing. and at the time we wre told it was her chemo. but the breathing continued to worsen and she also began to swell from fluid build up, and her pain became increasingly worse. She had zero appetite. the breathing eventually turned into a "gargle" sound that was always there.
I can not tell you how long your mother has but I will be glad to answer any other questions you may have about my mother's symptoms. Every case is different, but I have found recently that every case is also more similar than we would like.
I really do hope this will help you in some way. I will be praying for you and your family. Please let me know if you would like to talk again.