Does Surgery Required To Remove The Hardening Of The Right Breast?

hello Dr. I am 30 years old. I delivered baby on 20th sept. 2010 and after delivery i noticed a hardening like in my right breast(i had fibroidectomy on the same breast few years back) i m breastfeeding. on USG dr. told me its fat, he told me to remove it after 3 months, but since i m breastfeeding i dint go for the surgery. Can it create me future health hazard or it can be cancerious if i dont remove it? Please advise.