Suggest Remedy For Swelling In The Left Labia And Painful Urination

Hello I'm 22 years old and I've been married for 4 years. I had sexual intercourse one night with my husband he gave me oral and was fine that night. The next day we went out and I used the public restroom but I put about 2 paper seat covers. The next day I got my period and I started getting really itchy so I scratch down there and I cut myself. It started to burn but I left it alone since I knew that I did that to myself (I cut my self on my right side but not on my labia) three days later I started getting pain so I checked myself with a mirror and I saw my left labia swollen and red. It hurts to pee, I can't touch it and I have to be careful how I sit or lay down. I want to know how I got this and what's it called I know it's not herpes. Thank you for your help.