Can chemotherapy make Alzheimer's worse?

My 77 yo mom was diagnosed with cancer four months ago. It is a jaw cancer near the bone, and she is having treatment with Cetuximab (Erbitux) once a week and the tumor has shrunk already 50% after four sessions, and the pain is gone. My question is, how bad are the side effects from this drug? I notice that her Alzheimer's now is worse after she started the treatment. Otherwise she only had some skin rash and nothing else, but I'm not sure what to expect. Thanks for your help!