What Causes Fluttering In The Vagina And Anus?

Hi. I feel vibrations/fluttering in my vagina and anus. It normally happens around the time I am supposed to get my menstruation. Before I started using Ocello, it was a buzzing feeling, and now it is a fluttering around the anus and vagina opening. I am 28, and I chalked it up to just getting older. Any idea what may be causing this? Is is hormonal?