Alloderm left behind after extenders removed due to chronic inflammation
If your Alloderm has completely incorporated into your tissues, it's unlikely that it is responsible for your symptoms. More likely, the inflammation from your infection and scar from radiation and surgery are responsible. Post mastectomy coordinated rehab (directed through your physician) may help.
Also, at some point you will be a candidate for reconstruction again, but the reconstruction will likely take the form of autologous tissue.
Your situation sounds a bit complex. If you have had 36 rounds of radiation I would guess this it the radiation more likely than the AlloDerm that has caused tightness and neuropathy. Residual AlloDerm typically does not cause pain or tightness and I do not think it is contributing to the frozen shoulder. It sounds like you might benefit from consultation with a pain management specialist and from an appropriate course of physical therapy. Wishing you good luck.