Lump just under my breast closer to rib

About 3 years ago I noticed a lump under my breast and just over my rib cage.  I didn't think anything of it.  It's been there but since it didn't bother me I just forgot about it.  Recently my mother was diagnosed with Cancer on her left breast, She has already had her right breast removed.  She is 80 almost.  I am 57.  So when this came up, I decided to do a self breast exam.  I felt the same lump under my breast and not on my breast.  But when I poke or prod at it, I do feel some discomfort and not pain.  I have read so many posts about pain and the severity of pain.  Fast forward to now.  I last checked it about 4 days ago and it was there.  This morning I checked for it and it seems to have disappeared.  I know it will come back because I've had it for quite some time.  I have a Dr appointment on Feb 11, 2016 and pray that it is nothing.  If any of you who read this post have had similar problem, please share your story with me so that I know more or less what to expect.

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