My mother has metastatic breast ca (to bone only) after 7 years post op , took arimidex for 6 months, cea went up a wee bit. Dr changed her medicine to aromasin. Taking it for a week. Complains of headache nausea, and very increased joint pain, and tiredness,some insomnia. Do these reactions reduce over the time taking the aromasin? Or will they always be this bad? She did not take the drug today, will abuptly stopping the medicine have immediate bad consequences? We are waiting for a doctor to return our call but wanted another opinion.