What Causes Recurrent Pain In Sternum Area Of A Breast Cancer Survivor?

I am a two year breast cancer survivor. I have recently had recurring pain in the sternum area. I called my oncologist and he passed me off to my breast surgeon. When I called that office, I was told to wait until my next checkup which is in 3 weeks. Should I demand to be seen by one of them immediately?! I fear the pain is from a lump I found at the edge of my sternum near the breast implant.