Arm Pain constant and thinning. It's in the opposite arm to where I had my breast cancer. Should I mention this at my follow up appointment next month?

Good evening. 

Can anyone relate? I was treated for stage 1 grade 2 Hers2 pos invasive breast cancer 21 Months ago successfully. Following on from this, for the past couple of Months (maybe longer), I have been suffering with left arm pain (constant) and note that arm is thinning (opposit arm from previous breast cancer. My bones seem to hurt. I have a follow up breast scan next month. Should I mention this at breast clinic?