E.S.
Mnay years ago when my now 33 year old daughter was little I had the same problem and immediately paniced because my Mom had just died from breast cancer. The way the pediatrician explained it to me it was a residual of hormones from me from birth and that it would go away. She was also bottle fed and that issue never even came up. I would go to a new Dr. also but relax and try not to worry it is probably nothing.