Why are my labia minora and majora swollen and my vaginal opening tender, i am very concerned and worried even though. i have not had sex and especially haven't had any stds. what should i do and how can i check at home?

Do some detective work. This is often a reaction to soaps/creams/lotions or other agents that came in contact within the day preceding the finding. Even scented toilet tissue has done this. Panties that were laundered in a new soap, especially those with scented additives could be the trigger. A thin local application of hydrocortisone cream after gentile cleansing may provide some relief.