New breast pain 20 years post lumpectomy

I had a right breast lumpectomy with radiation treatments almost 20 years ago. There was no lymph node involvement. I was on Tamoxifen for 5 years. About a week ago, my right breast starting hurting like a deep bruise with a slight burning sensation. It is only on one side of the breast and is most noticeable in one very tender spot. Is this normal? Should I go to my Primary Care doctor? I no longer see an oncologist.