Hello there, im very sorry to hear about your mum! My mum has recently been diagnosed with stage 4 lung cancer, which is incurable, so they are giving her chemotherapy to prolongue her life. I'm not giving up hope! 

Similarly to your mum, mine is extremely skinny and has got a very very small appetite. Did your mum recieve a 'buk me up' handguide with the diagnosis? The booklet provides lotso of helpful information regarding things which are best to eat, meal plans and guides on how to cope with the loss of appetite. I have recently purchased a blender for my mum, so that she can have fresh soups/smoothies, so when she doesn't feel like eating, she can drink it instead! Another thing i've given her Is protein shakes, and I am thinking of giving her some food supplements too!

Another thing you could do is contact her Lung Cancer nurse, who is there to answer any questions, and provide some help in regards to why your mum isn't eating. Perhaps they could help with the pain, if the painkillers she is using aren't working. 

Is there any food that your mum absolutely loves and craves often? Perhaps get lots of that in stock!

Something which has really pushed my mum to eat, is positive energy. My siblings and I have remained very positive around her, which has given her a huge motivation to beat this cancer, she is doing anything and everything she can to do that! Maybe if she was to speak to people who are going through the same thing, it would serve as motivation? You could even speak with her about joining this website. (Unless she's anything like my mum and can't use the computer)

Lots of positive energy coming your way!

All the best

Sophia x