I too had radiation that resulted in fibrosis of the muscles of my chest wall, the intercostal muscles( the muscles between the ribs, and my pectoralis major and minor muscles. This was confirmed with CT. I also had lymphedema post radiation. PT with a breast cancer therapist helped enormously!! With radiation you do have the risk of developing what is now called pulmonary pneumonitis. This can occur up to five years out post radiation. If you have not seen a pulmonologist, you should. Do I still have pain and stiffness. The answer is yes, but my PT program has made it so much better. I wish you and any one else who have dealt with these issues the best!!