Sharp pain in back after expanders

Hi everyone. I've been dealing with breast cancer for a year and a half now. 1st time it was found I had a lumpectomy and radiation.  They also took a lymph node to be sure it wasn't spreading. A year later they found it again.  So this time I went more aggressive with treatment.  I had a double mastectomy with reconstruction. Also a lymph node removed. I wanted the implants above the muscle but they were put below.  Ever since they were put in I've had pain in my back directly around from the front side the radiation was done on. Of course all the radiation did for me is make everything resistant to stretch.  It's all so tight I can't even cough. So does anyone know if my back is related to the strain from the expansion? Is there anything that can help? Will it all loosen up after the implants go in? My doctor told me it has nothing to do with it.