I Had Breast Cancer In 2010. It Was Cdis And

I had breast cancer in 2010. It was cdis and I had a lumpectomy and radiation. Have been cancer free since. Last week my oncologist informed that i have had anemia for a couple of years. It went up slightly on one test and back down on the next. These tests were every 6 months and I wasn't told the results of the blood work. she informed me last wk of this anemia and told me we could do one of two things. We could do a bone marrow biopsy or 5 injections of chemo. This hit me out of the blue so I chose to put it off til my next 6 month appt. Now I don't know what to do or what she is looking for other then cancer. Shouldn't we do something else before we go to an invasive test or chemo?