As you know, I speak as one fighting cancer, and my perspective is a bit different than most on this board. The first thing you need to do is relax, and try to find peace in your situation. Anxiety and fear are two of your worst enemies. You especially need to try face this cancer objectively (difficult though it is). Your approach should be that of a general planning a great battle. Understand what would happen if this general were gripped with fear and anxiety. The battle is lost before the first shot is fired.
Next, you need to consider your objectives. I guess that you now understand that advanced metastic disease is far more serious than the common cold, and those on this thread who suggest any different speak in ignorance. They have not spent enough time with enough different patients with advanced metastatic disease. Anybody who has spent enough time with enough people with advanced metastatic disease (clinically verified) understand this. Your focus should be:
1) Complete eradication of the cancer.
2) If #1 is not obtained, stopping the progression of the cancer.
3) If #2 is not obtained slowing the progress of the cancer.
4) If #3 is not obtained, maximize health to enjoy the best of the time.
This is what nutritional therapy can offer. If you read Dr. Gerson's book, you will see that some of these were the results that his different patients had. But the protocol was the same for each patient, and he never could explain the different results, since often the worst recovered, and some far less serious never responded. One thing Gerson noted was that the patients who did die experienced minimal pain, and enjoyed the life they had left.
If you have your mom on a frantic and stressed routine then that is part of the problem. Whether she lives 5 months, 5 years, or 50 years, life is more than just having a pulse. Re-establish her routine so that she has some enjoyment. Take walks. Visit the beach, or a museum, or the woods. Be thankful for every day that you have, and make sure that each day you find some enjoyment.
Now, for your mum.
First, seriously question the chemo. Ask the doctor to show you hard evidence that the chemo will help people in your mum's situation. I doubt that he will be able to provide any, and absent strong evidence of benefit, the chemo will only further destroy your mum's health with no upside potential. Beware the chemo death spiral. I have seen it often. Chemo can make one die an agonized painful death much sooner than they would have if left alone.
Second, talk about the nutrition with mum. She needs to be active in this battle. Most cancer patients simply do what they are told, and hope that if they do everything right, they will be OK. This does not work. Mum needs to take control of her situation. She needs to assume full responsability for her health.
Third, establish your nutritional program, and stick with it. You can not try every single treatment proposed on this site. Poor mum will be taking 25 different types of enemas, and gagging down every nasty concoction known to mankind. Find meals that mum enjoys. Make juices that she does not have to gag down. A diet of 65-80% raw, and organic for the most toxic produce is good. Juice at least three times a day. Do periodic juice fasts (3-10 days per). Take at least one daily enemas (coffe and/or "food-grade" peroxide). Take the high-dose vitamins and the anti-oxidant suppliments that we have resomended (let me know if you want my list).
Fourth, mum needs exercise. If she can only walk one block, then walk one block. Every day.
Last, and most important, consider the Lord, and your place with Him. For those of us who know Him, death has no sting. Absent the fear of death, I fight my cancer objectively, and methodically, one day at a time.
Blessings and prayers to you and your mum,