hi, thank you for providing the brief history of you. A thorough musculoskeletal assessment is advised. By reading the history I could understand that this pain will be due to costochindritis. For this I can advice you is rest with breathing exercises. There are various types of breathing exercises and also it has benefits. 1. Deep breathing exercises 2. pursed lip breathing exercises 3. costal breathing exercises 4. abdominal breathing exercises 5. diaphragmatic breathing exercises. NOTE - while performing this exercises you should place the hand in the painful area to provide support. Also, as you mentioned in your history about the thyroid cancer, performing this breathing exercises will help to improve the strength in the muscles of the respiration. Also, due to breathing exercises there will be a good oxygen carrying capacity of blood and the body will be detoxified. The cellular mechanism will improve and the drug absorption capacity will also improve to reduce the symptoms of thyroid cancer. Breathing exercises also Improved the metabolism and also immune system. You can even perform slow general exercises without any strain to Improve the blood circulation as well. You can discuss the same with your oncologist. in my clinical experience I had a physician having thyroid cancer, we planned a rehabilitation containing the breathing exercises and general exercises along with the onco prescription. things turn out well and the optimum results were achieved. Regards Jay Indravadan Patel