I've Been Off Chemotherapy For Breast Cancer For A Year.

I've been off chemotherapy for breast cancer for a year. My white cell blood count has been a 7 for several months. Last month it was 3 and then it went up a bit. Yesterday it was below 3 and my oncologist said this was abnormal so he took more blood work to send for further evaluation. My bones on my legs have been hurting but he said this was due to tomaxacin medication. I'm really worried and my next appointment us not until the 13th. What can be causing my blood cells to become lower?