Sorry to hear about your problem but I am glad that you are seeking medical advise for that. Tamoxifen helps in keeping the cancer under control and prevents recurrence of breast cancer
. It is associated with some side effects like hot flashes, cervical hyperplasia
(for which you require PAP smears), DVT (clot in the veins), osteoporosis
(bone mineral density has to be done), cataract formation. Tamoxifen is not associated with renal infections or renal stones
Did you CT show the presence of stones? Any pus cells in the urine? MRI is not a good investigation to look for renal stones. You can go for a plain X-ray KUB.
You should also consult your oncologist
and have your symptoms evaluated.
Hope you get well soon.