question: i have a large lump on the joint of collerbone and breastbone on the left side a noticed it a few months back when i got pains in my shoulder. the lump hasnt changed in size but can be quite painful the pain comes and goes but the lump stays the same. i went to the doctor few months ago he sent me for chest xray but didnt find anything. at night if i sleep on my stomach and put my arm up and stay like that for to long i cant move the pain is aggonising it also hurts when i try to turn over the pain spreads across my shoulder some times in my arm and back to it always seems worse at night but once rested is better by morning it gets worse through the day especially when i lift something heavy like my children do you think it could be something serious.