Your vagina have yeast bacteria living inside it. This is normal. When outside yeast or dirt is introduced into the vagina, the yeast bacteria starts to grow and grow and grow, causing the very itchy yeast infection. Especially anything sweet or sugary or scented is likely to cause this.
You have a constant flow of fluids out of your vagina as your vagina cleans itself and your cycle changes your hormones. This is normal and it should not smell or itch. It can change color depending on where in your cycle you are. This discharge is a fluid. When you get a yeast infection, there are more solid chunks in the discharge, often described as a cottage cheese like discharge.
Yeast is easy to treat with a cream from your pharmacy.
The other causes can be the hair growing back, but that is outside on the outer lips. A bacterial infection called bacterial vaginosis (BV) but that discarge have a most foul fishy smell.
Did you have safe sex? Did you protect yourself from STDs and pregnancy? Normally a condom will prevent all the infections.