I'm sorry to learn that you are having all of these side effects, especially when your surgery and treatments are more than a year ago. I believe that these symptoms may have an element of lymphedema, which is a side effect of some surgeries and also of the radiation treatment. The breast tissues are also easily infected causing recurrent mastitis in the presence of lymphedema. Non pharmacologic remedies for this would include avoiding skin puncture, avoiding hot baths or warm temperature exposure of the area, and wearing loose clothes. I suggest that you discuss this possibility with your surgeon.
Regards and God bless.