Redness of the breast 3 years after treatment

Villagegirl1234

I finished my treatments for stage 1 IDC 2013. This November I developed an area of redness 4" by3" in the area above where the scar is from the lymph node removal. It is sometimes tender, puffy, and warm to the touch. I went to my specialist and she treated it's an infection. The area did not change on the antibiotics and at the follow up appt she said she was not worried. Any suggestions