19 year old married. fish smell. treated it like a yeast infection monistat. despite no thick discharge or itch. std free.smell isn't going away. help?

Probably BV: Probably a vaginal condition known as bacterial vaginosis. Non sexually transmitted, fishy odor, anti fungal medicine would not help. Contact your healthcare provider for oral or vaginal medication.

Not yeast: What you have is an overgrowth of bacteria - called BV or bacterial vaginosis, not a yeast infection. There is effective treatment - you will need a prescription from your doctor.