I had a mastectomy(DCIS) 4 years ago,left breast. Had a mammogram last month and all checked out well. I had been feeling a burning painful sensation in my right breast and was anxious about my mammogram, but was relieved when it came back ok. Two days ago while showering, I noticed there was a sore, slightly swollen lymph node under my right arm.(actually it is in the upper outside area of my right breast next to arm where my are bends).Sort of hard to explain exactly where it is. I am assuming it is lymph node. Should I be concerned? Thank you