bubble popping sensation near vagina

Baby has been head down for over 10 weeks now. I'm 37 weeks today. I often get this feeling very low in my pelvis like right above where the clitoris begins, it feels like air bubbles/bubbles popping!! Or maybe flutters? Vibrations? It's painless, just weird. I've actually had in every now and then for weeks but lately it's very frequent. What the heck is it!?? 
Update: I tried googling it and read that it could be "bulging bag of waters" which is apparently very serious. Freaking out!!! Anyone????