My dad had a lot of issues with nausea but they were not related to chemo or radiation so I can't help with some personal experience here. But I am sure that others will be along soon that can offer some personal help. But for my dads nausea, he had to try a wide variety and combinations of meds to get some help with that.
In the meantime, here are some links that may be of use to you -
http://www.macmillan.org.uk/Cancerinfor … iting.aspx
http://cancerhelp.cancerresearchuk.org/ … /sickness/
Also, have you used the search function here on the site as I know that you will find a ton of posts about this issue. I hope that you can find something that works for your mum here.
My best wishes to you and your mum,
Any advice or comments I give are based on personal experiences and knowledge and are my opinions only, they are not to be substituted for professional medical advice. Please seek professional advice from a qualified doctor or medical professional.