Treatment for fat necrosis after breast reduction

Hello,

My mother had a breast recution a couple weeks ago.  She had implants removed and went from a DD to a C.  I am not sure how much tissue was removed.  About a week after her surgery, her right nipple turned black and she had an apple size necrotic mass removed.  The biopsy came back that she had a bacterial infection, so the surgeon left the wound open to heal by secondary intent.  We have been taking good care of the dressings and everything seemed to be healing ok, but then her right breast started to get hard.  The surgeon believes the necrosis is spreading and he will have to open the right brest to remove the tissue.  

My mom has been using heat (one of those microwavable hot/cold packs), and has been using a hand massager to attemt to break up the "hard" tissue.  

At this point we are unsure what to do.  What causes necrosis?  Is this common?  
She is also complaining about being really tired...could that be related?
Should my mother get another opinion?
I am open to any thoughts, suggestions, shared experiences...anythiung...

Thank you,