I am 21 yrs old, still a virgin, bt a white substance comes out of my nipples whenever i squeez it. have skin prblm so takin medicines, zimax&roaccutane?

Multiple causes : The discharge could be the normal discharge of apocrine sweat glands found normally in the nipple. If it is more significant discharge, it may be due to galactorrhea, a condition in which milk is produced at low levels even without pregnancy. Although this can occur on it's own, it sometimes is associated with underlying hormonal changes. See your ob/gyn for evaluation and work up of this issue.