You have to go to a doctor. If this is an STD, you need prescription antibiotics. If it is yeast, you can use over the counter medicine.
But you have to find out.
For example, garnerella needs flagyl.
Chlamydia or gonorrhea need the correct anti bacterial.
2 grams of azithromycin will cover both...but you have to know with testing.
At age 26 you should have been getting pap smears to screen for cervical dysplasia and HPV...so this is over due.