mammo showed something in node...

I had my 6mo mammo today and they called right after and said that they saw something in a node.  I go in for an ultra sound tomorrow.  I talked to the nurse and my onc office and she said not to worry cause it happens ike this a lot.  they just want to be careful that they check everything.  For the last couple weeks i have had shoulder pain that goes down my arm.  Also i have a cord running under my arm.  I googled it and it said it was cording??  Anyway, what do you think?? 

I used to post here while going thru my treatments in the her2+ forum but can't remember my name or password...lol