Lump appears in last 15 days at 1year old DCIS lumpectomy site.

I'm sure you and your mom are nervous about a painful lump.  It's scary after going through what she's already been through.  I know first hand.  I was diagnosed Feb 2014 with DCIS .  It was found at lumpectomy.  Had 2nd lumpectomy to get clean margin followed by radiation.  I'm still on tamoxifen.  

Nov. 2016, I had two painful lumps appear in same breast.  One was about the size of thumb print and the other just smaller than diameter of pencil eraser.  I had lots of other stuff going on and getting it checked had to wait until Feb. 2017.  The mammogram in Feb. confirmed yes something there.  Same day I had an ultrasound of that breast. They said it could just be a change  from scaring and radiation but it needed further study.  They scheduled me for MRI of my breasts and needle core biopsies of the lumps.  Diagnosis was necrotic (dead) fatty tissue.  My surgeon suggested we monitor for 6 months and redo mammogram on that breast. He said sometimes the body would re-absorb necrotic fat and leave a dimple and the pain may go away.  He said sometimes it doesn't and if it's too painful they can surgically remove it.  

I feel like the largest lump is now smaller, making a dimple and almost no pain.  I feel like the small one hasn't changed. I had repeat mammograms on that breast on 8/9/17, this time they were 3D mammogram, radiologist said not any change since Feb.  The 3D mammogram did reveal a new small area of concern.  They feel like it is benign and is a result of so much scarring.  I'll have another 3D mammogram in Dec. if no further changes they will let me go back to mammogram every 6 months.   

Everyone's body is different.  Encourage her to get it checked out.  I'll be praying that she gets good news.