Dear porterp: Skin on the beasts is like skin on any part of the body and is subject to developing a variety of abnormalities. Things to consider, given that this is happening to both breasts are whether you are using any new soaps, lotions, fabric detergents, bras etc. These are common causes of itching. If there is a sore, a dermatologist may be best equipped to evaluate this if it does not heal. The mammogram and ultrasound will give more information that will help determine if any further evaluation is necessary.
Inflammatory Breast Cancer causes breast itching and pain. Many who have been diagnosed complain of spots which appear like bug bites. The itching and pain do not subside after using creams or steriods. This disease is OFTEN overlooked and misdiagnosed. Regular mammography does not show it. MRI's are recommended or biopsies. Even Biopsies have missed it. Be responsible for your health, and if the symptoms persist, don't let it rest.