16 wks, Weird symptoms, 2nd pregnancy

Help! So since last week my inner vagina has felt heavy. I looked in the mirror, and (tmi) can't see my vag hole anymore? There's some lump from inside my vagina that has swelled down into the opening? I can push it back up, but it is still there. I'm going to call my MW on Tuesday, but I was curious to see if anyone else has had this weird sensation/happening? Feels Almost like you have a tampon in but it's not in the whole way. I was scared of prolapse, but that doesn't make sense here. I had an internal ultrasound at 9 weeks exactly and everything was normal. Anyone?