Vulvar Lichen Sclerosus: A chronic inflammatory skin condition that can cause intense pruritus and burning sensation, especially at night. The negative bacterial swabs support this diagnosis, as it is not caused by a bacterial infection.

Vulvodynia: A condition characterized by chronic pain, burning, or discomfort in the vulva, without an identifiable cause. The symptoms worsening at night are consistent with vulvodynia.
Candidiasis (Yeasts): Although the bacterial swabs are negative, a fungal infection like candidiasis can cause pruritus and burning sensation. It's possible that the swabs were not tested for fungi.
Contact Dermatitis: An allergic or irritant reaction to soaps, detergents, or other substances can cause pruritus and burning sensation in the vulvar area.
Atopic Dermatitis (Eczema): A chronic skin condition that can cause pruritus, burning, and discomfort in the vulvar area, especially if the patient has a history of atopy.

Invasive Cervical Cancer or Vulvar Cancer: Although rare, it's essential to rule out malignancy, especially if the patient has a history of abnormal Pap smears or other risk factors.
Herpes Simplex Virus (HSV): A viral infection that can cause painful blisters, pruritus, and burning sensation in the vulvar area.
Syphilis: A bacterial infection that can cause a range of symptoms, including pruritus and burning sensation in the vulvar area, especially in the secondary stage.

Lichen Planus: A chronic inflammatory skin condition that can cause pruritus, burning sensation, and discomfort in the vulvar area.
Psoriasis: A chronic skin condition that can cause pruritus, burning sensation, and discomfort in the vulvar area, especially if the patient has a history of psoriasis.
Neurological Disorders (e.g., Neuropathic Pain): Certain neurological disorders can cause chronic pain, burning sensation, or discomfort in the vulvar area, without an identifiable cause.