I have unexplained deep ache in up right back 2 yrs. Mri spine ok. Chest xray ok. Mammogram ok. Ultrasound rt breast ok. Could this b missed tumor?

No test is 100% accurate, but with a normal spine MRI, it would be exceedingly unlikely for your back pain to be due to a tumor. Breast cancer would not present as back pain either.
Back pains. Right upper back pain is in the territory of the right kidney. You need to address the issue with abdominal and pelvic ultrasound since you could have a stone or obstruction of the right kidney secondary to bladder obstructionby stone or gynecological tumors causing secondary obstruction to the right kidney. The retroperitoneal region could harvest a tumor or fibrosis or referred pain from lungs.