Hello Doctor. My Problem Began Couple Years Ago. Harp Pinch

Hello Doctor. My problem began couple years ago. Harp pinch from inside vagina and then itching and pinching one of vaginal lips. Next day pimple appears. It has white head and big red swollen from inside. Pulsing pain. I make hot camomile tubs to relieve pain. 4-5 days and everything is fine again. It happens ones in 3-5 months. Sometimes ones in 4-5 weeks. It is not connected with weather, cloth, soap, food, stress. Herpes is negative. WET is negative. Husband doesn't have any problems.
Thank you.