My mom said its probably just a yeast infection but i don't have discharge it's just itchy & really swollen on the left side of my vag so i'm not sure?

Listen to your mom!: Wise mom: these are typical yeast symptoms. Usuallly no discharge or only a little. Could be herpes if sexually active and blisters/sores. See a doc for diagnosis and treatment. If sexually active and don't want mom to know, teens can be evaluated and treated for STDs and genital infections without parent's permission, often at low or no cost, e.g. at health dept, Planned Parenthood clinic, etc.