My inner lips are swollen after masturbation

You do not have to feel embarrased or make excuses. What you do in private is fine as long as it is healthy. Masturbation is there to help you manage your sexual urges and it is pretty healthy and good for you.

Swelling is normally due to friction and heat, or an allergy. Make sure you use a water or silicone based personal lubricant. Do not rub to hard, or for too long. If you are using a toy, make sure it is clean, smooth and well lubricated.

Keep yourself dry and clean. Wear cotton panties, sleep without panties (if safe to do), avoid nylon and tight fitting pants, wash with clean water and your fingers, spray yourself off with a small spray bottle after urinating, pat yourself dry, do not wipe.

You can try an ice pack, wrapped in cloth to prevent ice burns, use an NSAID pain killer if neccisary. Monitor yourself for a yeast infection.

If this does not go away within a few days, speak to your mom.