Reddit: Really need advice on a family matter

I'm not really sure what to do, so I'll explain the situation and I would really appreciate any guidance from fellow redditors that have been through something that may be able to help me.

So, I'll begin my story, my mother has been sick for about 2-4 years. Pretty seriously ill. Doctors passed her around to one another, as no one knew or could find anything wrong with her. Several tests were done, and repeated. These tests include CT scans, endoscopy, colonoscopy, x-rays, etc. As far as I'm aware, they had performed damn near every examination you can perform to a human being. During this time period, no doctor could diagnose the problem and would send her back disappointed and hopeless, all the while her condition was worsening. The doctors also had very poor communication with each other, so it would take weeks to a few months when a new doctor would take her on in order for anything to get done (nearly all of them repeated tests). Usually after the doctors would find nothing, they would dismiss her and prescribe her varying medication (usually pain pills and more Xanax). Finally, a doctor at a prestigious local hospital found a problem he though was the cause of her pain and weight loss. At this point, she had gone from ~140-145 to about 105 pounds (My mother is 5 foot 9.5). So this was pretty much a walking skeleton. Anyways, the doctor believed that there was a special type of leak in her pancreas leaking fluid into her abdominal areas causing serious pain. This was a huge relief to my family, we finally had hope.

At this point, I was basically accepting that my mother was going to die at the age of 55 (I'm 21). During the surgery, they found a tumor in her intestines which they believed to be cancerous, and after tests, we found out that it was indeed cancerous. Now, the silver lining in this mess was that the tumor was operable, and they think they got it all. To this day, we still think she is cancer free. The problem with all of this is that during the 2-4 year time period of doctors passing her along prescribing heavy doses of pain medication/Xanax she became addicted to the medicine. She refuses to let anyone monitor her pills and very commonly mixes and matches her pills into different bottles where only she knows which is which. During her recovery from essentially 2 surgeries, and dropping down to about 95 lbs at her lowest, she nearly Overdosed on Xanax. So, in the emergency room, the nurses basically told us that she was so addicted to Xanax that if she tried to quit cold turkey, it could kill her. It was such a big deal, that the person that prescribed this to her, was fired on the spot.

Now, the problem I've got, my mother still has a prescription for Xanax, refuses to let anyone monitor her pills, and I'm beginning to recognize the signs of her taking too much again. I know her regular physician that she goes to did not talk to the emergency room doctor or the surgeon that removed the cancer/fixed her pancreas.

My sister and I have already tried to talk to the pharmacy and the doctor. We can receive no information regarding her prescriptions, nor can we talk to her primary physician without her being present about our concerns because of confidentiality.

Thank you for sticking with me for this long if you read this whole thing. What can I do to help Reddit?

Sorry for the grammar and probably terrible separation of thoughts into paragraphs. I tried to organize all of my thoughts on the fly.

tl;dr - After many doctors passed my mother's cancer by with medication, she is addicted to Xanax and refuses to believe it.

EDIT1: tl;dr added...