Of course you should go to the DR!!! It might not be breast cancer but there are all kinds of other things it could be. (not to freak you out, but better safe than sorry) I have a disease that is called neurofibromotosis..that is a bif fancy word for masses that grow from the lining of my nerves. They are harmless until they grow on something of importance. I had one removed from my paraspinal area earlier this month that had grown to the size of a grapefruit!! I still have others that are marble size-in my forearm & one in each thigh...they don't hurt & aren't causing any damage. Please go to the dr-tell them you want a cat scan or something!!! I waited to long to have my tumor removed from my back & I now have that lovely thing called cancer. Procrastination will get you no where...It is your body & if something is freaking you out - go check it out!!!