My Daughter Has Just Completed Chemo And Radiation For Saliva

My daughter has just completed chemo and radiation for saliva gland cancer. three weeks ago... surgery was first then chemo and radiation... her face is still swollen and painful after 5 months... and she has become so quick to snap and everything makes her angry to the point I'm beginning to worry she will have a stroke! is this "normal" I mean she wasn't listenrd to and this went on for almost a year until I got involved and yelled at people.... no one would help her... I'm angry too .... but is the change in her attitude due to the treatments?