It is normal for your lips to be uneven.It is not because there is anything wrong, or because of masturbation, or anything else. Your whole body is uneven. It may not seem that way, but it is. It is just more noticable and pronounced in your inner labia, breasts and feet.
Wash your vulva with normal clean water and your fingers, no soap. Get a small spray bottle and spray yourself off on the toilet, instead of wiping. Pat yourself dry. Sleep without panties (only if it is safe to do so!), wear panties wiith a full cotton crotch. Avoid synthetic pants and tight fitting clothes..
Use a different brand of pads next month. It might be an allergic reaction to something in the pads.
Use an ice pack (wrap it in cloth to prevent ice burns) on your vulva to make the swelling and itch go away.
Monitor yourself for an infection. A change in your discharge and itchyness are normally a good sign that you have an infection.
If it does not go away, you will have to talk to somebody.
Best of luck!