Hi,
Welcome to the forum.I am glad to help you out. The pains which are occuring in the lower back could possibly be due to endometriosis.
Endometriosis is the presence of normal endometrial mucosa abnormally implanted in locations other than the uterine cavity.
It can also be one of the causes of abnormal(prolonged and occasionally painful) uterine bleeding. Pelvic ultrasound or an MRI can help in making the diagnosis. However, laparoscopy is the diagnostic procedure of choice.
Regarding the breast pain, if you feel the lump, then you need to consult a surgeon and get yourself examined and possibly do a mammogram.
The commonest cause of breast pain is fibroadenosis which is usually treated by routine painkillers. Please do consult a gynecologist too. I sincerely hope that helps. Take care.