I am numb I don’t know what is happening

i care for my 96 year old mother who has lung cancer

the last few days she has complained of back ache and asked for more morphine through the night but this morning she was vomiting constantly and in excruciating pain so I called the district nursr

she has given her an injection to ease the sickness and relieve the pain she told me it would sedate her for a few hours and she may need more

I am not medically trained or updated but am I at a stage where I need to be ready to say goodbye or could mum get over this 

any advice would be good at the moment