What Is The Treatment For Inflammation And Swollen Labia Majora?

One of my labia minors is swollen and inflammed. I have not been sexually active, last menstrual cycle was about ten days ago. No discharge, odor or pain when urinating. Is tender to touch but mostly just uncomfortable. It happened very suddenly, it was normal in morning yesterday after work I noticed it. What could this be and is there otc tx?