Hi.. The adam's apple referred to as thyroid cartilage is not a bone.. It is an cartilage and forms the begining of the trachea... A small structural abnormality in the cartilage is not of major concer as long as the breathing is not affected.. If you do not have any symptoms, then you do not have to be concerned..
I do not have an Adam's apple, as I am a female.. It does not feel like a lump, just an extension of bone up the right side of my neck.
What this sounds like to me is a subluxation of the clavicle bone. I wouldn't be able to tell for sure without actually examining you or seeing your x-ray. Since this is what I suspect, you can find a doctor who can correct this problem here: http://www.kevinhearon.com/CEA/cceplocator.html