Hi @Sister, did you gave nodes out? The nerves get stretched around the lymphatic system when interfered with. Nerves are notoriously slow to heal unfortunately. Gentle two finger massage over the area if you can stand it, touching the area is good (I kniw it feel yuck over the numbness) water from you shower head to stimulate it. Have a chat to the nurses while you in for next surgery for a good pain relief regime. Back of my arm is still numb many months on and I still get occasional discomfort - it's just slow.
Oh and do you have one of the breast post op cushions??? Xxoo