Ultra sound and mri the new lump breast. It may not have showed up as cancer on mammo. Your oncologist is right. I am a mammo tech and religiously got my mammo every year. A few months after mammo and ultrasound I felt a rock lump in left breast. I immediately went in for mammo and ultrasound. Mammo did not show lump 11mm. I had ultrasound and was neg I made tech redo ultrasound with my finger pointing to lump. They saw it but not on mammo. I had mri and it showed the cancer after i had lumpectomy it was 9mm after lumpectomy. I had ILC cancer. My surgeon explained that ILC is like cobwebs and does not necessarily show up on mammo. The xray of mammo machine may not show the tiny cobwehu6b configuration of the ILC. Anyway.. go with your oncologist being thorough have all the testing available. to you. It is vigilance the rest of your life that will get you through. Good luck!