Recurrence within 2 years and still ER + despite Tamoxifen

Hi 

I recently found a lump below my armpit on side where I had mastectomy 2 years ago. Originally had DCIS and small 11mm invasive ER +8. No rads or chemo then. I found a New lump Recently and biopsy shows it is 4mm invasive ductal carcinoma ER + 7! So basically Tamoxifen hasn’t worked looking at probable chemo and surgery, seeing Consultant this week. So scared it’s spread and also waiting for CT/ bone staging scans. Anyone had similar? Wonder what they can use instead of Tamoxifen? 
Siân :two_hearts: