I had fatigue as well but it passed after a few weeks. The breast tissue post radiation was very hard , and after initially being able to,lift my arm easily over my head before radiation, it then deteriorated and became painful,about 3 months post radiation. Breast tissue was quite hard and painful . I’ve checked in with a physio who,specialises in breast cancer patients and am now massaging the breast / armpit tissue daily in order to,break down the fibrosis/scar tissue .(i was a lumpectomy patient ). I have a few exercises too to do to,strengthen arm .Not all will develop post radiation issues but be aware of it and seek help if it occurs