breast cancer

Hi I'm 51 I had no symptoms of breast cancer but had my first ever mammogram in January this year by February 11th I had a biopsy and lumpectomy with couple of lymph nodes removed had radiotherapy and I'm on tamoxifen for five years just wanted to know if anyone feels like me I can be fine for a few weeks but four or five days a month I feel this overwhelming heavy tiredness leg aches blurry eyes which makes it hard at work ,when it goes it's like something lifting off me and I'm back to normal for a few weeks again.I also have a tender armpit at moment is this normal