as much as i would like to help you it would not be prudent for any medical professional to blindly make such an important call over the internet. it would be strongly advised for you to see a medical professional. someone who can delve into your relevant medical history and someone who can examine this "lump" first hand.
i have a lump about 2-3inches under my arm on my right side half way down my rib cage. what is it? . i've never had a lump before. also i have a mole on my neck all my life. it is normally very dark brown nearly black. it is now the same as the color of my skin. could this be linked together with the lump?