Male breast tissue
About 1/2 males will undergo a transient nipple/breast enlargement at he onset of puberty.
Carrying extra weigh aggravates the issue as part of the enlargement is fat.Most will resolve slowly as other hormonal changes kick in over about a year. If the process is unchanged after 2-3 yrs ; you've made an effort to lose any extra weight, it is time to discuss it with a surgeon. No meds will fix it.