How is the first mamo after lumpectomy??? Painful?

I love that I found this message board to help all of us discuss & manage our journeys. I am 70 years old and was on HRT for 20 years & was diagnosed in March with Invasive Ductal Carcinoma Grade 1, HER/PR +, HER2 neg, tubular. It was found at a reg yearly mamo & had a biopsy & then lumpectomy with clear margins followed by 5 radiation treatments. My oncologist wants me on tamoxifen but I so far declined due to the side effects I have watched my friends endure & I was told mine is slow growing. I have my first mammogram this Wed. & my breast is still sore with a knotty feel above the nipple. Is this going to be painful?
Thx a million in advance for any words of wisdom.