According to the symptoms that you mentioned (“neck and mouth got big”), you may experiencing an allergic reaction to the medicine. Allergic reactions are totally unpredictable and the only solution for treating them is to change the medicine. A drop in blood count is a common side effect for all chemotherapeutic drugs and can’t be avoided. The only thing that can be done is to stop the treatment and wait until the blood count gets better. Breast cancers that have hormonal receptors (are hormone positive) can be also treated with estrogen inhibitors (tamoxifen). Local radio-therapy is also used for preventing local recidiv after surgical removal. For proper treatment, you can consult an oncologist.