Radiation is supposed to cause shrinkage. I had a right reduction (I was a DDD), left partial mastectomy (half the breast) with reconstruction. It was purposely left a little bigger, because radiation would shrink it. It didn’t. I worked with OT, trying to move the edema out, no success. That was 5 years ago. Initially, I had a really hard time with it, and all the scars. I have accepted the new me, plus smaller breasts are better!

So in case anyone comes across this - it was an infection :( inside, I had no symptoms for a long time other than the swelling. The discomfort slowly turned to pain and I didn’t realize how bad I was feeling until I developed a fever (even taking Tylenol and Advil round the clock due to pain). I was started on oral antibiotics and the pain and fever/ flu like feeling subsided but the swelling never went away. Took those antibiotic pills for 2 weeks.
2 weeks after finishing, I was still swollen, and then pain and malaise feelings came back with a vengeance - red, hot skin on my chest too. Went to the ER at my drs orders and had a bad infection. They drained it, removed the expander (it had burst at some point) and I was put on super IV antibiotics and oral antibiotics and pain meds (Morphine for about 2 days bc the pain wouldn’t let up until it was drained and I had been on IV antibiotics for a few days). Anyways, dont ignore swelling! I was in the hospital for a week bc I did, thinking it was just normal radiation side effect.