Yes, as the post above me states, it is normal. My mother took chemopherapy for almost two years and only way later she wouldn't have such strong side effects, however I do recommend keeping her hydrated and letting her rest ( also try to give her something light to eat, eating heavy food might make her vomit ).
Hope the best for your mother and that it will help her!
This is a normal side effect the best thing you can do is support them trying to eat and make sure they stay hydrated. Hope everything is ok.