my 14 yr old son has been complaining of tenderness and a small knot directly under his right nipple. it appears slightly inverted- left one appears normal.. i thought it was probably a normal part of puberty , but today he told me it had began leaking clear fluid... i believe it only does this when he presses on it and he says it is very sore to touch. is this something to be concerned about? he is the youngest of 4 boys and the first time we have encountered this problem...