Anyone have back pain following breast radiation?

Although I did really well using creams and gels to prevent breast fibrosis during radiation, it never occurred to me to do the same to my back. I work out on a rowing machine and following one longer session, my back hurt. (I'm 2 months out from treatment. )Upper muscles, not lower back. Never had this before. The left side resolved after 2 days. but the right upper back still hurts. I write for 4-5 hours a day and that's become challenging. Did some research and yes, the back muscles are affected by those radiation beams. I wish I'd known!