Vibrating vagina! Any one else?

So since this is baby number 6 and I have never EVER had this. On pregnancy forums i have seen other ladies mention it and I was like wth is that!! ? yesterday I started noticing it and it's continued into this morning. It's so low it can not possibly be the baby vibrating. It feels almost like my bag of water vibrating directly on my cervix. sure strange and new for me. A one else have this or a suggestion on what it is??? (aside from baby itself bc I know babies can have seizure like movement as their nervous system develops and that's not what this feels like)