Discharge from a male nipple can be a sign of a precancerous condition. This is especially true if the discharge comes from only one nipple. When I was in my early 20s if I pressed my right nipple about 6 drops of clear fluid would pop out on the tip. Nothing happened if I pressed the left nipple. The doctor removed my right breast as a precaution.
If I were you I'd talk to my parents right away so they could take me to a doctor. Yes, it can be just a response to the hormones your body is now producing during puberty, but there's a chance it can be mastitis, which is an infection. So you really should see a doctor, as soon as possible.
I'd ask your parents to set up a doctor appointment. While it could be something related to hormones activating your body along with other puberty changes, it seems more like you might have mastitis. Get seen by a doc.