The pain you are experiencing can be a complication of surgery, especially after an extensive surgery. Patients are advised to undergo physical therapy after surgery to prevent contracture and scarring that can eventually cause pain.
Gabapentin can help relieve the neuropathic pain. You may want to consult also a pain specialist.
the pain you may be feeling may be the start of lymphedema anything can trigger it, watch for swelling in your hand and arm Good luck
I agree with Dr. Dennis. PT (Physical Therapy) really helped me. just make sure you find someone good and hopefully one who is also trained in lymphedema massage. I am snot saying you have lymphedema but it helps to have someone who knows about bc complications.