Hi Thank you for asking HCM. I have gone through your query. Labia is a very sensitive part. Harsh or violent sex can give some injury and cause swelling. Yeast infection is another possibility. Avoid soaps and irritants to wash the area. Use saline or warm water for washing. If condition persist then a local examination by gynecologist or GP and a swab test should be done. Applying creams with combination of corticosteroid like hydrocortisone and anti fungal like clotrimazole will be helpful also. Hope this may help you. Let me know if anything not clear. Thanks.