Dear curiousinAZ: A new lump in a breast that does not go away needs to be evaluated. It is certainly possible that this could be a lymph node and breast cancer is uncommon in 23 year old women. However, without an examination, it is not possible to speculate on what this might be.
I must also add that I haven't had any stress in my life lately and I was getting a pretty good nights sleep when these broke out which my doctor told me could also cause these.