Before first menstruation
teenage girls may have brownish discharge with clots which are stringy. This is a way how a young female organism prepares for menstruation.
As you are not sexually active we can rule out a std
.Stringy stretchy discharge is typical for ovulation. If in addition you have ovulation spotting, that may be brownish, you’ll get this kind of discharge. It looks like egg-white cervical mucus with brownish admixture, no unpleasant odor.When brown stretchy discharge occurs instead of period, it may be a sign of bacterial or yeast infection.
From all these you should rule out infection first.In that case you might need antibiotics.And you will be fine after clearing that infection if you have.For that better you should have a gynecology consultation.
hope this may help you