hi,
Thanks for the query.

the possible causes of your symptoms are,
-infection leading to edema and cellulitis which will present with swollen, red and tender labia,
this can happen because of skin getting infected because of scratches etc,

-sensitive reaction can occur because of contact dermatitis to soaps, deodorants, contraceptive creams etc,

-formation of hematoma due to any injury,

as you are having severe pain better to contact gynecologist as early as possible to find out the possible cause and treatment can be taken accordingly,
mean while you can try methods like keeping ice packs on swelling, taking analgesic tablets etc to get some relief.


Hope I have answered your query. I will be available to answer your follow up queries. If you are satisfied with all my answer, please rate the answer after closing the discussion.
Take care.

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