Mom is sick, swollen breast, any advice?

555daughter

Hello! his is my first time using this site. I am concerned about my mother. She received a lumpectomy aprox. 1 yr. ago, also had 10 lymph nodes removed, all on her right side. She was healing well and has reconstructive surgery schedualed for September, then about a month ago became very ill (while in Ontario on a trip, during a heat wave). Her breast became very swollen, red, and sore, and she experienced chills and extreme fatigue. Mom went to see her oncologist upon returning to Calgary, by then the swelling was subsiding, and the doctor was "not concerned". Well yesterday it started again, Mom is very sick, can't go to work (she opened a new business recently) and her breast is bright red, swollen and sore. She said she had a hot bath Tuesday night, by Wednesday was feeling awful. Is this a type of lymphedema? Any advice?