Mastectomies four years ago....now another lump

Hello Ladies.  I am new to this forum, but not to breast cancer.  I was diagnosed with DCIS in right breast in 2007, and in 2008 I had a double mastectomy and skin sparing TRAM reconstruction.  Now, over four years later I have found a lump.  

After my mastectomies and reconstruction I was told I would need no further mammograms.  Last week I found a sizable lump that can easily be felt and even seen if I am lying down.  I saw my breast oncologist day before yesterday.  He is referring me to a breast oncologist surgeon who he feels will want to remove this lump regardless of ultrasound and fine needle aspiration results.  He said it could possible be a lump of necrotic tissue, say, if a blood supply to that area failed and the tissue it supported died.  He said if this is a malignant tumor, he does not expect it to be of the original tumor....but to have arisen from the small amount of tissue left after the skin sparing procedure.  In other words, a completely new and different tumor.

 I am waiting on test scheduling for the ultrasound and fine needle aspiration, consultation with breast surgeon. 

 My head is spinning.  I thought I had reduced my chances of getting any kind of breast cancer by 99%!   When I search for my particular situation on the internet, I don't get a match.  Can someone please talk to me if their situation was or is similar?

Many thanks,

Lauren