Bone Marrow Biopsy

I have been experiencing fevers, swollen lymph nodes, fatigue and constant getting sick for over a year now. Have been tested for what seems like everything. They did a lymph node biopsy in Nov - which came back as reactive but benign. Just had a gallium scan and it showed that I have abnormal activity in my spine, hips and long leg bones. The summary said due to bone marrow infiltration or leukemia. Have had constant blood tests - and always low RBC. My WBC varies - sometimes slightly high and then within range. The gallium also showed slightly enlarged liver. Dr now wants to do a bone marrow biopsy. He is thinking this is just related to the anemia and the biopsy will show this. First, how much to these biopsy's hurt? i am very nervous about it. Also - did anyone have a "normal" WBc and still came back with leukemia diagnosis? I have other blood levels out of range such as elevated ESR, RDW and low b12 and iron. I thought I was done with biopsies when my lymph node was done - now the worry starts again. Any replies are appreciated!