I am 34 year old male over the last

Patient: I am 34 year old male. over the last two months or so the area behind and around my right nipple is very tender and hurts to the touch. its not the nipple itself, its behind and around it. just recently i can feel what feels like a flat mass behind it. very thin and just bigger than the nipple itself.. almost like a silver dollar behimd my nipple. when i press hard it hurts. any ideas?

Doctor: