Sorry to hear about your mum getting breast cancer again.A similar thing happened to me.I had a lumpectomy and radiation for breast cancer back in 2003.In 2010 it came back in the same breast,same spot. So I had to have a mastectomy of the left breast,followed by chemotherapy,then onto Tamoxifen for 5 years.Since the last operation,I have a constant discomfort across my chest scar -feels like sticky tape across my chest and it's pulling. My surgeon says it's adhesions cos I lost skin elasticity from radiation.I'm not sure if this is what your mum has? Blog here anytime for help and support -you are a thoughtful daughter and a comfort to your mum,I'm sure.Look after yourself as well.
Tonya xx