Hi,
Welcome to the forum. There are a few possibilities for your symptoms.First of all,mammary duct ectasia has to be ruled out. It causes one or more of the ducts beneath your nipple to become inflamed and clogged with a thick, sticky substance.
Second possibility is of galactorrhea which is a feature of hormonal imbalance, such as from taking birth control pills,an underactive thyroid gland.tumor (prolactinoma) or other disorder of the pituitary gland and chronic breast stimulation, such as from frequent breast self-exams or sexual activity.
Third possibility is of intraductal papilloma.It is a small, usually noncancerous (benign) growth that projects into a milk duct near your nipple.
Confirmation can be done only after mammogram for which I sincerely advise you to consult a gynecologist.
I hope it helps. Take care and regards.