Hi C, I think it's definitely worth getting your arm checked out if it's causing discomfort but I also had pain post-radiotherapy on opposite side (neck and shoulder) of the affected area. I think it was because I was using this side more and sleeping on this side more to avoid using my surgery side. The discomfort has eased as my surgery side has got back to normal and I'm using it more for everyday tasks but no harm in chatting to your breast nurse about it. 

Thanks so much. I'm in for immunotherapy this week so will mention x

Best of luck with it C!

I had terrible pain in both shoulders after radiotherapy. It took 3 months and massage to make it better. Phone your breast cancer nurse and they will help you. Dont worry on your own. I worry with every pain too. Its normal to feel this anxiety and others have told me it gets less as time goes on

Thanks Lainey. Helps to know this.

I’m going through the same at the min.  Had my opp in aug and started getting pain ! Can’t sleep On the side of the pain they said it was infected.  Going to get checked this week

Hello C, sorry to hear you're in pain. I too had the same, radiotherapy to left breast but agony in right arm.  As Case has already said I think it was because I was relying more on my right arm to do day to day tasks and I was only sleeping on my right side. The radiologists had to physically lift and place my right arm during the sessions as I wasn't able to move it myself and it was agony. Hopefully, as time goes on your pain lessens, mine did quite quickly after the 15 sessions of radiotherapy finished. I'd speak to your clinical team and ask if you can take painkillers or if they have any further advice.

Good luck Liz

Thanks Liz. Was the same trying to get my right arm up and out of the "stirrups". Got some pain relief to take and trusting I've just overstretched or pulled something x