Hi Emmie,
Welcome to the site- So sorry to hear about your mum, it is such a shock when something like this comes out of the blue. I know others will post with more advice than I can give you, but I am on European time, so am probably the first to read it. My dad , who lived in the UK , had metastatic cancer, and we were put in touch with a Macmillan nurse- if you can speak with them, I would highly recommend you to - they are totally committed to help cancer patients and their families, and as this is their speciality, they are usually more informed on how to deal with problems, such as for example nausea, than your GP. I think if you go on their website, you can actually call and speak to one of them, or be put in touch with one in your area. I don·t know what is causing the nausea, but it may be connected to the medication Mum is on.
Thinking of you both, Diane