Hi,
Usually if there was a cut or tear within the vagina, you would also experience bleeding and sensitivity. Unfortunately, you can't be diagnosed online, you need to make an appointment for a pelvic exam with your doctor or gynecologist to figure out what is causing this pain, swelling, and itching. Meanwhile take an anti-inflammatory med. (like ibuprofen), soak in a warm bath 2x daily, and wear cotton underwear.
Take Care