Dead skin

I have had a double mastectomy with immediate reconstitution with tissue expanders two weeks ago. My left breast is doing amazing but my right breast tissue is dying. About 4cm by 3.5cm is black. This is at the bottom of the breast where the sling was created to hold the implant in place. I am not old, I don’t smoke, I don’t drink. I exercise 6 times a week and am fit. I am heathy weight and yet it still happened to me. I am in the process of having the dead skin dressed every other day hoping that the skin underneath is still alive. Has anyone else been through this? I am finding it really hard to come to terms with. It looks disgusting. I am trying to be positive that it will be ok and that I won’t have to have another operation to remove the tissue expander and dead skin and go flat. I feel sick and can’t stop crying all the time, Pam