My left nipple has been itchy for years,it's less sensitive than my right.the itch drives me crazy, it's not red,has no rash,i'm not breastfeeding. the nipple looks perfectly fine except for that itch.so my question is what's causing this horrible it?

Nipple symptoms : This type of sensation may very well be secondary to a nerve that is being stimulated in your skin. However, it is important to make sure the tissue behind your nipple in the breast is normal and thus I would recommend discussing this with your women's health provider. The ducts that go from your breast through the nipple could be involved and a mammogram may be necessary.