This is a good example as to why I may get rid of my internet.   I'm sorry, but I don't like to criticize, however, the fact that she is feeling warmth and it has been happening for 3 years without any visible signs (on the skin or shape of the breast) does not mean that this isn't something the woman should be concerned about.  This could go on for 13+ years before seeing any signs that might not be detected on a mammogram, but by then, if it's cancer it would be too late.  I know because that is precisely what happened to my mother.  Also, I've had the same symptoms, yet the masses were NOT perceptible on a mammogram, and guess what?  The doctor suspects it might be cancer (I'll find out after my biopsies this week).   LISTEN TO YOUR DOCTOR and be prudent about this.  You should not worry because that never helps, but you should be proactive in making sure you get a sonogram of the area.   Also, if the doctor(s) say that it isn't absolutely necessary to remove the area, if and once they pinpoint it, go with getting it removed.