Hello, i am a 20 year old female and for some reason i have very itchy, sore nipples.what are the possible causes?

Try this: It could be eczema/ dermatitis, irritation. Try some cortizone, (hydrocortisone) neosporin combination 2x a day have your annual mammogram and feel for any abnormal breat lump as well. If without improvement, go see your dr.

Contact or irritant: There is a condition called runners nipple, it occurs from rubbing on shirts, etc. Vaseline or a topical steroid may help. There are cases of breast cancer on the nipple, so make sure to get a proper evaluation!