Secondary bone scan

I was diagnosed with Breast cancer 8 months ago. ER+ PR+ Her2 - , 0.4 mm grade II invasive ductal. no chemo. No radiation . I take tamaxofin.Last 2 weeks I have unbearable pain in my knees and hips. I think may be it's related to secondary bone cancer. I had bone scan 8 months ago and had lots of X-ray about 20 and 4 Ct-scan chest and mamogram (mammogram) ..I heard about the risk of radiation and i'm worry about it. what can i do to notice if my pain related to arthritis or no? Is it possible without X-ray? Can tumor marker can detect secondary bone cancer? What can i do to avoid the risk of cancer?

[Cleveland Clinic]

Dear mocibat, Pain in your knees and hips could be due to many things including arthritis.  Without evaluation of your symptoms through testing and physical exam it is impossible to say what is causing your pain.  Tamoxifen is used to block estrogen and is used as adjuvant treatment (treatment given after surgery to try to prevent or minimize the growth of microscopic deposits of tumor cells that might grow into a recurrent tumor) of hormone receptor positive breast cancer.  

[mocibat]

Thanks for your answer. WHat exam should I do to detect it? Another bone scan? how often can I have bone scan?