Need advise on very large lymph node. Possible recurrence?

Hi ladies- what a wonderful site. I was very active 7 yrs ago when my mom was first diagnosed with bc. I have several concerns and wonder if anyone has had a similar situation, as we are all so worried at the current time. Mom is 62, first diagnosed seven yrs ago with idc left breast, 3'oclock position, 2cm, er/pr positive, her2 neg. had lumpectomy with sentinel node biopsy. Node was clear, but margins of tumor were not, so mom did a bilateral mas. with tram. Horrible experience, developed blood clot and huge hernas, which had to be removed. She has been doing great on hormone therapy for 5 years. Did not have chemo, as oncotype score was 17. Now we are dealing with a very large left side under arm lymph nodes. 4 enlarged, one the size of golfball. At first oncologist said she was not concerned, but after mammogram and ultrasound we all began to worry. Needle biopsy was performed on two nodes, still waiting on results. No tumor was noted from mammogram or ultrasound. Had lung scan and was all clear, liver enzymes are fine and all bloodwork normal

So confused?? Can anyone help? Thank you so much. Any advice is appreciated.