As said in our puberty101 FAQ ;
I have found little lumps that sometimes hurt when I touch/try to move them under/around my nipples. What are they?
These are called nodules and these are common, they're just fat deposits that will go away after a few months/years. It's nothing serious and nothing to worry about.
Our Puberty101 FAQ covers a lot of questions so take a look at it before posting as your question may have already been answered. That way you can get answers faster.