My dad was diagnosed with colon cancer which has spread to liver and nearly the whole of liver was effected.  The oncologist gave a prognosis of 3- 6 months 11 weeks ago as dad refused any treatment 

 I have seen a real decline this week in my dad , he sleeps or does most of the day. He has had a couple of falls which luckily someone has caught him before he reached the floor . He has list so much weight and a lot of his muscle mass and eats very little.

He said he feels his time is near , he is able to use the toilet independently and wash and dress himself but it tires him . 

My question really is can things go from " relative normality" to death quite quickly . The dr and nurses suggest the dying can progress very quickly and out of no where .

Can anyone help or offer any information or advise please on what happens next