Welcome to HealthcareMagic. From the symptoms it looks like the friction rub or chafing during intercourse has caused this swelling of labia especially if intercourse was done with less lubrication. The other reason can be an allergic reaction
to soaps, detergents, shower gel and condoms etc. Apply cold
compresses and wear cotton undergarments. Application of mild corticosteroid cream and oral antiinflammatories like ibuprofen/acetaminophen
are also helpful. If the symptoms persist then consult a gynecologist.
Hope it helps you. Regards.