I've had a large (a bit larger than a kidney bean), hard, movable lump inside of my neck for 3 or more years. I first noticed it 2-3 years ago, but for all I know it could have been there for decades, or my entire life. It isn't at ALL on the other side of my neck. It's snuggled deep, between my trachea and the muscles on the right side of my neck. Where you'd push in to feel a pulse. So it feels like it's at an... "organ depth"? It's not right under the skin, by any means.