I've got a tiny hard ball type thing under my skin just above my armpit (on the side joining my arm). It's been there for about 18 months and about a year ago I went to the GP and had a scan. They said it was so small it could barely be seen on the scan so it wasn't anything to worry about and would probably go away. It's still there, I'm not sure if it's any bigger but if it is it's by a tiny amount. Would you go back to the Dr or just assume it's a cyst? Apologies for the blurry armpit photo!