My lovely Dad has pancreatic cancer. Lately he's been getting confused and his personality has started to change. Has anyone else experienced this?

Hi I've been looking after my parents,My dad always looked after my mum and now he's got pancreatic cancer since September last year he's not managed to have chemo since Christmas.He keeps getting chest infections.Latley he's been getting very confused and personally is changing he is not like the same person any more not like my dad I don't seem to recognise him they way he used to be .It's so difficult!I love my parents so much and my mum seems to be deteriorating with all the stress .I'm running both houses food shops and helping were I can.Has any one else had personality changes with this type .