Mother with cancer

Good evening all, Happy new year to you all and hope you're all keeping well :)

I'm currently caring for my 69 year old Mother. I'm finding it quite hard at the moment and after some advice. I'll post the story below and hopefully get some advice. 

In 2018 she went for a eye test and they say something behind the eye then they sent her to an eye hospital which showed a tumor behind her eye. We went to a different hospital in Sheffield and they told her she had melanoma behind the eye about 3 weeks after the appointment she had a operation to remove the eye and the cancer had thankfully gone. She then had to go for liver checks every 3 months.

In June this year, she went for MRI/CT scan which showed 2 lesions on the liver, we went for futher test a week after, and then I phoned the GP about 2 weeks after the test and they told us no action required(which we assumed was good news) so I booked a holiday for September to her favourite place as a treat. During the time since June and the scans, she was suffering bad back pain and down her legs, and the doctors treated her for arthritis.She wasn't also eating but the GP said that was the side effects from arthritis drugs

Three days before the holiday, the doctor phoned and said the scans showed she had cancer in the spine, lungs, bones and liver. He also said the doctors surgery shouldn't have told us no action required and he would be investigating. I didn't tell her the bad news at the time because I wanted her to enjoy the holiday best she could. I felt bad keeping it from her but I was doing it to be kind. A week or so after the holiday, she was in agony with her back and had to call ambulance and she was in hospital for 2 weeks. We still hadn't heard from the GP/Doctors regarding the bad news about the cancer before the holiday and was still being treated for arthritis. 

Whilst she was in hopsital they finally got round to the cancer with painkillers and morphine which she has been on since September. 

She had a biopsy in November to see what treatment they could offer and had the consultation 3 weeks ago: they've offered her immunotherapy(not sure which one) but with a 10% chance of being successful and with high risk of very bad side effects. She still is in two minds if to try the immunotherapy, as last time she was in hospital, I couldn't visit and if she has a bad reaction then she may be back in hospital. The consultant we saw was stern and straight to the point which I guess they have to be but it had put doubts in Mums mind. She didn't want to know what would happen if she didn't have the treament - she has bad anxiety and struggles to take things in. 

Over Christmas she was in bad pain, they increased the dosage of the drugs but don't seem to be having a effect on the pain. She has got a bed in the living room, and I'm at home all day now to look after her. My work have been very understanding and have given me from Sept - April off with pay so one less thing to worry about. 

The nurses from the hospital are ringing this week to see if she has a answer if she would like to try the treatment so thought I'd post on here to see if anyone has any simular situations or advice. 

Sorry for the long message.

Take care

Martin